LIBRARY 


UNIVERSITY  OF  CALIFORNIA. 


Class 


! 


ANALYSIS  OF  MIXED  PAINTS, 

COLOR  PIGMENTS,  AND 

VARNISHES 


BY 

CLIFFORD    DYER    HOLLEY,  M.S.,  PH.D., 

Professor  of  Industrial  Chemistry,  North  Dakota  Agricultural  College,  and 

Chemist  on  the  Staff  of  the  North  Dakota  Experiment  Station.   Joint 

Author  of  Paint  and  Paint  Products ;  and  Paints  and  Their 

Composition.        Formerly   Chemist  for    the   D.   B. 

Hand   Company,  Scranton,   Pennsylvania 


AND 


E.  F.  LADD,  B.S. 


Professor  of  Chemistry,  North  Dakota  Agricultural  College, 

State  Chemist  and  Food  Commissioner  for 

North  Dakota 


FIRST  EDITION 
FIRST   THOUSAND 


NEW  YORK 
JOHN  WILEY  &  SONS 

LONDON  :  CHAPMAN  &  HALL,  LIMITED 
1908 

•  VX^ 

OF  THE  \ 

UNIVERSITY  ) 

OF  / 


T? 


GENERAL 
/h*t 


COPYRIGHT,    1908, 
BY 

C.  D.  HOLLEY  AND  E.  P.  LADD 


Stanhope  ipresa 

F.    H.   GIUSON     COMPANY 
BOSTON.      U.S.A. 


PREFACE. 

THIS  book  was  written  primarily  to  meet  the  needs  of 
the  author's  own  classes  in  Industrial  Quantitative  Analy- 
sis, and  it  is  given  to  the  public  in  the  belief  that  there  is 
a  demand  for  a  concise  work  on  the  analysis  of  paints 
and  paint  products. 

Numerous  books  have  been  written  during  the  past  few 
years  dealing  with  the  subject  of  Paints,  discussing  in  a 
general  way  the  properties  of  the  various  pigments  and 
their  methods  of  manufacture.  But  the  author  is  not 
acquainted  with  a  single  work  that  will  serve  as  a  guide 
to  a  chemist  of  ordinary  training  in  taking  a  can  of  mixed 
paint,  of  practically  any  shade  or  tint,  making  a  complete 
analysis  of  it  and  furnishing  him  sufficient  data,  derived 
from  a  large  number  of  analyses,  so  that  he  may  interpret 
the  results  of  his  own  analysis  in  a  rational  manner. 

It  is  the  object  of  the  author  as  far  as  may  be  to  fill  this 
much  felt  want,  and  the  methods  given  in  the  following 
pages  should  be  of  interest  to  advanced  college  students 
who  may  wish  to  inform  themselves  on  methods  of  paint 
analysis;  to  the  industrial  chemist  who  has  more  or  less 
paint  work  to  do ;  and  especially  to  the  young  paint  chemist 
who  is  just  starting  out  in  his  career. 

Each  method  given  in  this  work  has  been  tested  out  in 
the  author's  laboratory  and  its  working  value  thoroughly 
demonstrated.  The  various  analyses  given  are  believed 
to  be  representative  of  the  composition  of  the  pigments 
they  illustrate,  and  it  is  hoped  that  they  will  be  of  service 
in  enabling  the  analyst  to  pass  on  paint  products  with 
fairness  to  both  the  manufacturer  and  the  consumer.  The 

iii 


iv  PREFACE. 

chapters  on  varnish  analysis  are  admittedly  incomplete. 
Our  present  literature  on  varnish,  and  especially  varnish 
analysis,  is  meagre,  and  much  of  it  of  a  contradictory 
nature,  but  the  author  hopes  in  the  near  future  to  be  able  to 
present  data  that  will  be  of  further  value  to  varnish 
chemists. 

In  conclusion  the  author  wishes  to  express  his  sincere 
thanks  to  Commissioner  E.  F.  Ladd  for  the  portion  con- 
tributed by  him,  and  for  his  kindly  guidance  and  interest 
in  the  entire  work;  and  also  to  Mr.  Clarence  E.  Kinney, 
who  has  assisted  in  much  of  the  analytical  work. 

C.  D.  HOLLEY. 

FARGO,  N.D.  Feb.  19,  1907. 


TABLE  OF  CONTENTS. 

PART   I. 

CHAPTEB.  PAGE 

I.    READY  MIXED  PAINTS 1 

Why  Paints  Fail;  North  Dakota  Paint  Law;  Groups 
of  Pigments;  Sublimed  Lead;  Lithopone;  Leaded 
Zinc;  Zinc  Lead  White;  Form  of  Label;  Labels 
that  Mislead ;  Need  of  Paint  Law ;  Water  in  Paint ; 
Imitation  White  Leads;  Paints  supposed  to  be 
White  Lead  and  Zinc;  Whitewash;  Short  Measure 
and  Weights;  Relation  of  Lead  to  Zinc. 

PART   II. 

I.   ANALYSIS  OF  MIXED  PAINTS 29 

1.  Preparation  of  Sample;  2.  Separation  of  the 
Vehicle  from  the  Pigment;  3.  Ratio  of  Pigment 
to  Vehicle;  4.  Typical  Analyses  of  White  and 
Gray  Paints;  5.  Composition  of  Colored  Paints; 
6.  Reds;  7.  Blues;  8.  Yellows;  9.  Greens;  10. 
Browns;  11.  Greys  and  Grays. 

II.   ANALYSIS  OF  THE  VEHICLE      36 

12.  Water,  Occurrence;  13.  Detection;  14.  Estima- 
tion; 15.  Linseed  Oil,  Extraction  from  Paint;  16. 
Estimation  of  the  Volatile  Oils;  17.  Specific  Grav- 
ity; 18.  Spot  Test;  19.  Mineral  Oils;  20.  Separa- 
tion of  Mineral  Oil  from  Rosin  Oil;  21.  Cotton- 
seed Oil;  22.  Corn  Oil;  23.  Fish  Oil;  24.  Rosin 
and  Rosin  Oils ;  26.  Linseed  Oil  from  Inferior  Seed ; 
28.  Specifications  for  Boiled  Linseed  Oil,  Navy 
Department,  1905. 

III.   ANALYSIS  OF  THE  VOLATILE  OILS      48 

29.  Analysis  of  the  Volatile  Oils,  Identification;  30. 
Estimation  of  Petroleum  Products;  33.  Analyses 
of  Volatile  Oils;  34.  Excessive  Use  of  Volatile  Oils. 


vi  CONTENTS. 

CHAPTER.  PAGE. 

IV.   SPECIAL  METHODS  ON  OIL  ANALYSIS 54 

35.  Determination  of  the  Iodine  Number;  36.  Prep- 
aration of  Reagents;  37.  Determination;  38. 
Iodine  Numbers  of  Various  Oils;  39.  Determina- 
tion of  the  Bromine  Absorption  of  Oils;  40.  Table 
of  Bromine  Values  of  Various  Oils;  41.  Estima- 
tion of  Rosin  in  Mixtures  of  Linseed  Oil  and  Min- 
eral Oil;  42.  Volumetrically ;  43.  Gravimetrically; 
44.  Determination  of  Free  Fatty  Acids  in  Linseed 
Oil;  45.  Determination  of  the  Saponification  Value; 
46.  Determination  of  the  Flash  Point  of  Linseed 
Oil;  49.  Evaporation  Test;  50.  Determination  of 
Flash  Point  and  Fire  Test  of  Petroleum  Products; 
51.  Covered  Testers;  52.  Open  Testers;  53.  Fire 
Test;  54.  Specifications  for  Various  Oils;  55.  Lin- 
seed Oil;  56.  Deodorized  Benzine;  57.  Engine  Oil; 
58.  High  Pressure  Cylinder  Oil;  59.  Lithographic 
Varnish;  60.  Kerosene  Oil;  61.  Lard  Oil;  62.  Sperm 
Oil;  63.  Gasoline. 

V.   ANALYSIS  OF  WHITE  LEAD 69 

64.  Color;  65  Lead  Acetate;  66.  Opacity;  67. 
Painting  Test;  68.  Sandy  Lead;  69.  Foreign  Pig- 
ments; 70.  Estimation  of  Carbon  Dioxide,  Knorr's 
Apparatus;  72.  Scheibler's  Apparatus;  75.  Typi- 
cal Analyses  of  White  Leads ;  76.  Determination  of 
Acetic  Acid  in  White  Lead;  78.  Analyses  of  Mis- 
cellaneous White  Leads;  79.  Short  Weights  of 
White  Lead  Packages. 

VI.   ANALYSIS  OF  SUBLIMED  LEAD,   ZINC  OXIDES,  AND  ZINC- 
LEAD  PIGMENTS      81 

Analysis  of  Sublimed  Lead;  80.  Lead  and  Zinc  Oxide; 
81.  Sulphates;  82.  Sulphur  Dioxide;  83.  Compo- 
sition of  Sublimed  Lead;  84.  Identification  and 
Estimation  of  Sublimed  Lead  in  Mixtures ;  85. 
Analysis  of  Zinc  Oxides,  Leaded  Zincs,  and  Zinc- 
Lead  Whites;  86.  Moisture;  87.  Sulphur  Dioxide; 
88.  Zinc  Sulphate;  89.  Insoluble  Matter;  90. 
Lead;  91.  Sulphuric  Acid;  92.  Zinc  Oxide;  93. 
Calculations;  94.  Classification:  (1)  Green  Seal  and 
Florence  Red  Zinc  Oxides;  (2)  New  Jersey  Zinc 
Oxides;  (3)  Mineral  Point  Zincs;  (4)  Leaded  Zincs; 


CONTENTS.  Vil 

CHAPTER.  PAGE. 

VI.   ANALYSIS  OF  SUBLIMED  LEAD,  ZINC  OXIDES,  AND  ZINC- 
LEAD  PIGMENTS  —  Continued. 

(5)  Zinc-Lead  White;  95.  Estimation  of  Arsenic 
and  Antimony  in  Zinc-Lead  Whites;  98.  Anti- 
mony. 

VII.  ANALYSIS  OF  ZINC  SULPHIDE  WHITES  AND  INERT  PIG- 
MENTS          92 

Analysis  of  Lithopone,  Ponolith,  etc.;  99.  Moisture; 
100.  Barium  Sulphate ;  101.  Total  Zinc;  102.  Zinc 
Sulphide;  103.  Zinc  Oxide;  104.  Calcium;  105.  An- 
alyses of  Zinc  Sulphide  Whites;  Analysis  of  White 
Mineral  Primer,  White  Ochre,  Magnesite,  Whiting, 
Paris  White,  English  Cliffstone,  etc. ;  106.  Moisture ; 
107.  Silica;  108.  Alumina  andiron;  109.  Calcium; 
110.  Magnesium;  111.  Calcium  and  Magnesium 
Oxides;  113.  Analyses  of  Calcium  and  Magnesium 
Carbonate  Pigments;  114.  Analyses  of  Agalite, 
Terra  Alba,  etc.;  115.  Analyses  of  Calcium  Sul- 
phate Pigments;  Analysis  of  Silicas,  Clays  and 
other  Insoluble  Pigments;  117.  Fusion  with  So- 
dium Carbonate.  119.  Moisture;  120.  Combined 
Water;  121.  Determination  of  the  Alkali  Metals, 
Sodium  and  Potassium;  122.  Analyses  of  Silicas 
and  Silicates;  123.  Specifications  for  Paste  Wood 
Filler. 

VIII.   DETERMINATION  OF  FINENESS,  COVERING  POWER  AND 

TINTING  STRENGTH  OF  PIGMENTS 102 

124.  Determination  of  the  Comparative  Fineness  of 
Pigments;  125.  Comparison  of  Paints  for  Covering 
Power;  127.  Determination  of  the  Tinting  Strength 
of  Colors;  128.  Chrome  Yellows,  Ochres,  and 
Greens;  129.  Reds;  130.  Blues  and  Blacks;  131. 
Paste  Goods ;  135.  Gravity  and  Volume  of  Pigments. 

IX.   THE  PRACTICAL  TESTING  OUT  OF  PAINTS 107 

136.  Paints  should  be  Tested  out  by  the  Chemist;  137. 
Equipment;  139.  Requisites  for  a  Good  Paint ;  140. 
Relation  of  the  Surface  to  the  Paint;  141.  Test 
Structures;  143.  Application  of  the  Priming  Coat ; 
147.  Oil  Reductions;  150.  Turpentine  Reductions; 
157.  Application  of  the  Middle  Coat;  160.  Applica- 
tion of  Third  Coat;  161.  Application  of  Paste  Leads 
and  Paste  Paints;  162.  Driers. 


viii  CONTENTS. 

CHAPTER  PAGE. 

X.  ANALYSIS  OF  WHITE  PAINTS 119 

164.  Qualitative  Analysis  of  White  Paints;  166. 
Quantitative  Analysis  of  White  Paints.  Total  Lead ; 
167.  Calcium;  168.  Magnesium;  169.  Zinc  Oxide; 
170.  Lead  Sulphate ;  171 .  Basic  Carbonate  of  Lead ; 
172.  Insoluble  Residue;  173.  Barium  Sulphate; 
174.  Silica;  175.  Alumina;  176.  Calcium  and  Mag- 
nesium Oxides;  177.  Mixed  Carbonates  and  Sul- 
phates; 178.  Calculations;  179.  Typical  Analyses 
of  Mixed  Paints;  181.  Calculation  of  Approxi- 
mate Cost  of  Mixed  Paints;  182.  Analyses  of  Sub- 
limed Lead  Paints;  183.  Analyses  of  Leaded  Zinc 
Paints;  184.  Analyses  of  Mixed  Paints  for  Inside 
Use;  185.  Analyses  of  Cheapened  Mixed  Paints; 
186.  Analyses  of  White  Paints  According  to 
Thompson. 

XI.   ANALYSIS  OF  INDIAN  REDS,  VENETIAN  REDS,  TUSCAN 

REDS,  RED  OXIDES,  AND  OCHRES 135 

196.  Hygroscopic  Moisture;  197.  Combined  Water; 
198.  Silica  and  Barium  Sulphate;  199.  Ferric  Ox- 
ide; 200.  Preparation  of  Reagents;  201.  Alumina; 
202.  Calcium;  203.  Magnesium;  204.  Analyses  of 
Indian  Reds,  Red  Oxides  and  Venetian  Reds;  207. 
Analyses  of  Ochres  and  Iron  Oxide  Pigments; 
208.  Specifications  for  Venetian  Red. 

XII.   ANALYSIS  OF  BLACK  AND  BROWN  PIGMENTS  AND  PAINTS.     143 

Analysis  of  Black  Pigments;  209.  Composition;  210. 
Moisture;  211.  Oils;  212.  Ash;  213.  Carbon;  214. 
Calcium;  215.  Phosphoric  Acid;  216.  Preparation 
of  Reagents;  217.  Magnesium;  218.  Calculations; 
219.  Specifications  for  Drop  Black;  220.  Speci- 
fications for  Carbon  Black;  221.  Composi- 
tion of  Ivory  and  Bone ;  222.  Analyses  of  Various 
Blacks ;  Analysis  of  Mixed  Paints  Tinted  with  Black 
and  Oxide  of  Iron  Pigments;  223.  Carbon;  224. 
Ferric  Oxide;  225.  Alumina;  226.  Zinc  Oxide; 
227.  Calcium  and  Magnesium;  228.  Residue  Insol- 
uble in  Hydrochloric  Acid;  229.  Lead  Sulphate; 
230.  Analysis  of  Paints  Tinted  with  Blacks,  Ochre, 
and  Iron  Oxides;  Vandyke  Brown;  231.  Composi- 
tion; 232.  Analyses;  Analysis  of  Umbers  and 


CONTENTS.  ix 

CHAPTEB.  PAGE. 

XII.    ANALYSIS   OF    BLACK    AND     BROWN    PIGMENTS    AND 
PAINT  —  Continued. 

Siennas;  233.  Hygroscopic  Moisture;  234.  Com- 
bined Water;  235.  Silica  and  Barium  Sulphate; 
237.  Ferric  Oxide;  238.  Manganese;  241.  Alu- 
mina; 242.  Calcium  and  Magnesium;  243.  Analy- 
sis of  Umbers  and  Siennas;  244.  Analysis  of 
Mixed  Paints  Containing  Umbers,  Siennas,  Ochres 
and  Chrome  Yellows. 

XIII.   ANALYSIS  OF  BLUE  PIGMENTS  AND  PAINTS 159 

Analysis  of  Prussian  Blues,  Chinese  Blues,  etc. ;  245. 
Hygroscopic  Moisture;  246.  Water  of  Combination; 
247.  Iron;  248.  Aluminum;  249.  Calcium;  250. 
Alkali  Metal  and  Alkaline  Salts;  251.  Cyanogen; 
252.  Barytes,  Silica,  Clay,  etc.;  253.  Calculations; 
254.  Analyses  of  Pure  Prussian  Blues;  255.  An- 
alyses of  Chinese  Blues;  256.  Analysis  of  Mixed 
Paints  Containing  Prussian  Blue,  Chinese  Blue, 
etc. ;  Analysis  of  Ultramarine ;  258.  Properties ; 
259.  Moisture;  260.  Silica;  261.  Alumina;  262. 
Sodium  Oxide;  263.  Total  Sulphur;  264.  Com- 
bined Sulphuric  Acid ;  265  and  266.  Analyses  of  Ultra- 
marines by  Author  and  by  Hurst ;  267.  Analysis  of 
Cobalt  Blues;  268.  Moisture;  269.  Alumina;  270. 
Calcium  and  Magnesium ;  271.  Cobalt  Oxides. 

XIV.   ANALYSIS    OP    YELLOW,    ORANGE   AND    RED    CHROME 

LEADS.     ANALYSIS  OF  VERMILIONS 166 

272.  Composition;  273.  Moisture;  279.  Barytes,  Sil- 
ica and  Clay;  275.  Lead;  276.  Chromium;  277. 
Calcium;  278.  Magnesium;  279.  Combined  Sul- 
phuric Acid;  280.  Calculations;  281.  Analysis  of 
Chrome  Leads;  Analyses  of  Mixed  Paints  Contain- 
ing Chrome  Yellows  and  Ochres ;  282.  Barytes,  Sil- 
ica and  Clay;  283.  Lead;  284.  Iron;  285.  Chro- 
mium; 286.  Aluminum;  287.  Zinc;  288.  Calcium, 
Magnesium  and  Combined  Sulphuric  Acid;  Analy- 
sis of  Vermilions;  289.  Properties;  290.  Detection 
of  Vermilionettes,  Para  and  Alizarine  Reds;  291. 
Barytes,  Silica  and  Clay;  292.  Lead;  294.  Estima- 
tion of  Lead  and  Mercury,  Calcium  Compounds 
Present;  295.  Ferric  Oxide;  296.  Zinc  Oxide;  297. 
Calcium  and  Magnesium;  298.  Calculations;  299. 
Analyses  of  Vermilions;  300.  Antimony  Vermilion 
and  Orange. 


X  CONTENTS. 

CHAPTER.  PAGE. 

XV.  ANALYSIS  OF  CHROME  GREENS  AND  EMERALD  GREENS.  176 
Analysis  of  Chrome  Greens;  301.  Moisture;  302. 
Organic  Color;  303.  Barytes,  Silica,  Clay,  etc.; 
304.  Lead;  305.  Iron;  306.  Chromium;  307.  Alu- 
minum; 308.  Calcium  and  Magnesium;  309. 
Cyanogen;  310.  Combined  Sulphuric  Acid;  311. 
Calculations;  312.  Analyses  of  Chrome  Greens; 
Analysis  of  Emerald  Green,  Paris  Green  and  Arsenic 
Insecticides;  313.  Properties;  314.  Water  Soluble 
Arsenious  Oxide ;  315.  Total  Arsenious  Oxide ;  316. 
Analyses  of  Paris  Green;  317.  Moisture;  318.  Ani- 
line Color;  319.  Insoluble  Residue;  320.  Lead 
Chromate;  321.  Copper;  322.  Arsenic;  323.  Chro- 
mium and  Zinc;  324.  Calcium;  325.  Magnesium; 
326.  Acetic  Acid;  327.  Analyses  of  a  Paris  Green. 

XVI.   EXERCISES  IN  COLOR  MAKING      184 

329.  Para-Nitoraniline  Lake;  330.  Crimson  Red  Lake ; 
331.  Emerald  Green;  332.  Pale  Lemon  Chrome; 
333.  Medium  Chrome  Yellow;  334.  American  Ver- 
milion; 335.  Chinese  Blue  No.  1 ;  336.  Chinese  Blue 
No.  2;  337.  Chinese  Blue  No.  3;  338.  Brunswick 
Greens. 

XVII.  ANALYSIS  OF  JAPANS  AND  DRIERS 188 

340.  Determination  of  the  Drying  Salts;  341.  Lead; 
342.  Manganese;  343.  Zinc;  344.  Calculations; 
345.  Determination  of  the  Volatile  Oils;  346. 
Separation  of  Benzine  and  Turpentine;  347.  De- 
tection of  Rosin ;  348.  Practical  Tests. 

XVIII.  ANALYSIS  OF  SHELLAC  AND  SPIRIT  VARNISHES  ....  194 
Analysis  of  Shellac:  351.  Detection  of  Rosin;  352. 
Estimation  of  Rosin;  354.  Iodine  Numbers  of 
Shellacs;  Analysis  of  Shellac  Varnish;  355.  Com- 
position; 356.  Determination  of  the  Body  of  Shel- 
lac Varnishes;  357.  Determination  of  Strength  of 
Alcohol  Used;  358.  Examination  of  Solvent;  359. 
Detection  of  Benzine;  360.  Columbian  Spirit  and 
Wood  Alcohol;  361.  Detection  and  Estimation  of 
Wood  Alcohol  in  Mixtures  with  Grain  Alcohol; 
366.  Detection  and  Estimation  of  Rosin;  367. 
Estimation  of  Rosin,  Mannhardt's  Method;  368. 
Practical  Test  for  Brewers'  Varnish ;  369.  Analysis 
of  Shellac  Varnishes;  370.  Damar  Varnish;  371. 
Tests. 


CONTENTS.  Xl 

CHAPTER.  PAGE. 

XIX.   ANALYSIS  OF  OIL  VARNISHES 206 

374.  Specific  Gravity;  375.  Viscosity;  376.  Separa- 
tion, Identification  and  Estimation  of  Volatile  Oils; 
377.  Separation  of  the  Resin  Gums  from  the  Oil, 
Twitchell's  Method;  379.  Separation  of  the  Gums 
from  the  Oil;  380.  Short  Oil  Varnishes;  382.  Long 
Oil  Varnishes;  383.  Determination  of  the  so-called 
Insoluble  and  Soluble  Gums;  384.  Detection  and 
Estimation  of  Rosin  in  Varnishes;  391.  Navy 
Specifications  for  Interior  Varnish;  392.  Navy 
Specifications  for  Black  Asphaltum. 

XX.  THE  PRACTICAL  TESTING  OF  VARNISHES 218 

394.  Smell;  395.  Consistency;  396.  Working  and 
Flowing;  398.  Time  of  Drying;  399.  Sponge  Test; 
401.  Toughness  and  Elasticity;  404.  Hardness;  405. 
Classification  of  Varnishes;  406.  Floor  Varnishes; 
407.  Interior  Varnishes;  409.  Exterior  Varnishes; 
410.  Short  Volume;  411.  Significance  of  Lime  in 
Varnishes;  412.  Table  of  Analyses;  415.  Trade 
Names  of  the  Principal  Paint  Pigments  with  Chem- 
ical Names;  416.  Atomic  Weights  of  the  More 
Common  Elements;  417.  Factors  for  Gravimetric 
Analysis;  418.  Measure,  Weights  and  Temperatures. 


PART  I. 


READY   MIXED   PAINTS. 

BY  E.   F.   LADD. 


xiii 


ANALYSIS  OF  MIXED  PAINTS. 


READY   MIXED   PAINTS. 

THE  rapid  increase  in  the  manufacture  and  consumption 
of  ready  mixed  paints  during  the  past  third  of  a  century 
has  been  quite  phenomenal.  To-day  it  is  claimed  that 
fully  70,000,000  gallons  of  paints  mixed  and  ready  for  use 
are  annually  consumed  in  the  United  States.  It  is  not 
strange,  therefore,  where  without  being  placed  under  legis- 
lative restraint  of  any  kind,  in  such  a  great  industry  and 
one  so  little  understood  by  the  general  public,  that  abuses 
have  arisen  which  will  require  courage,  persistency,  and 
legislative  action  to  correct. 

It  is  unfortunate  that  some  of  the  mixed  paints  have  so 
little  of  merit,  and  how  are  the  public  to  separate  the  good 
from  the  bad?  With  competition  so  fierce  as  has  been  the 
case  within  the  past  few  years,  it  is  safe  to  say  that  paint 
manufacturers  have  not,  as  a  rule,  produced  a  paint  as 
good  as  they  knew  how  to  produce,  but  rather  that  the 
best  of  them  were  making  as  good  a  paint  as  they  could 
sell  in  the  face  of  the  kind  of  competition  practised.  There 
are  many  other  manufacturers  producing  paint  as  cheaply 
as  they  can,  and  with  little  regard  for  wearing  quality  as 
a  first  consideration. 

The  writer  maintains  that  a  house  well  painted,  primed 
and  two  good  coats  applied,  should  not  require  re-painting 
for  protective  purposes  oftener  than  once  in  five  to  seven 
years.  If  every  condition  is  favorable  the  paint  may 
still  be  well  preserved  at  the  end  of  ten  years.  Not  a  few 

l 


2  ANALYSIS  OF  MIXED  PAINTS. 

houses  as  now  treated  need  re-painting  at  the  end  of  two 
or  three  years,  and  not  infrequently  the  old  paint  must  be 
burned  away  before  the  new  can  be  applied.  Something 
is  wrong  where  this  is  required,  —  not  always  the  fault  of 
the  paints,  sometimes  the  methods  of  application  are 
faulty;  conditions  existing  at  the  time  of  painting  may  be 
responsible  for  the  trouble,  or  the  paint  previously  used 
may  be  the  source  of  the  difficulty,  and  even  the  difference 
in  the  expansive  properties  in  the  two  paints  may  be  a 
cause  for  trouble. 

In  average  conditions  there  is  no  valid  reason  why  paints 
should  ever  crack,  peel,  blister,  or  pull  away  from  the 
wood.  It  not  infrequently  does  one  of  these,  as  well  as 
show  many  other  faults,  all  of  which  need  to  be  understood 
and  explained.  A  knowledge  of  the  chemical  and  physical 
properties  of  the  paint  are  the  first  essentials  for  under- 
standing the  reasons  for  these  faults  where  the  work  has 
been  well  done.  Why  at  times  do  paints  crack,  peel, 
scale,  blister,  or  pull  away  from  the  wood,  and  do  many 
other  unreasonable  things?  Why  in  some  instances  will 
the  paint  wear  well  when  the  house  is  painted  for  the  first 
time,  and  when  re-painted  with  a  different  paint  show 
many  of  these  faults? 

These  and  scores  of  other  questions  are  asked  by  the 
general  public,  and  they  are  demanding  an  answer.  They 
are  demanding  an  answer  from  those  in  whom  they  have 
confidence,  and  who,  from  their  position,  have  no  reason 
to  become  biassed.  Our  Experiment  Stations  must  furnish 
this  new  sought  for  information.  The  chemist  must 
acquaint  himself  with  the  subject,  investigate,  experiment, 
keep  in  touch  with  the  processes  of  manufacture,  and  aid 
the  consumer  in  arriving  at  a  rational  explanation.  He 
must  go  farther,  and  know  paints.  The  paint  manufac- 
turer's chemist  can  do  much,  but  he  is  usually  an  interested 


READY  MIXED  PAINTS.  3 

party,  and  a  more  searching  investigation  is  required  than 
he  can  command  time  or  means  to  give  to  the  problem. 
There  is  needed  such  investigation  as  only  well-equipped 
experiment  stations  can  command  for  such  a  study. 

The  North  Dakota  Experiment  Station  has  undertaken 
this  line  of  work,  and  has  erected  several  experimental 
paint  fences  of  the  type  shown  in  the  frontispiece  of  this 
book,  as  well  as  undertaking  to  conduct  paint  tests  on  a 
broad  scale  upon  a  number  of  buildings,  employing  various 
combinations  of  pigments.  These  tests  will  be  continued 
for  a  series  of  years ;  and  frequently  repeated  and  the  whole 
question  studied,  in  order  to  determine  what  is  best  with 
conditions  such  as  exist  in  North  Dakota  and  like  adjoining 
territory. 

Let  us  not  be  too  severe  in  our  criticism  of  the  paint 
manufacturer  until  the  full  truth  is  known,  and  this  as 
the  results  of  honest  investigation.  No  man  can  prevent 
the  dishonest  use  of  data  given  to  the  public  in  the  best  of 
faith  and  when  rightly  used  of  great  value,  but  in  the 
hands  of  dishonest  salesmen  distorted  and  abused.  The 
methods  of  salesmanship  usually,  however,  reflect  the  true 
character  of  the  house  behind  the  men,  and  therefore  are 
beacon  lights  not  to  be  wholly  ignored. 

At  the  present  time  nearly  all  families  are  users  of  paints, 
nevertheless  but  few  persons  are  familiar  with  the  compo- 
sition or  working  qualities  of  paints.  There  are  few  sub- 
jects of  greater  importance  to  the  builder,  since  the  appear- 
ance of  a  building  is  to  be  judged  largely  by  the  character 
of  the  finishing  coat,  which  is  paint.  And  yet  how  little 
the  average  person  knows  of  the  subject  of  paints.  Nearly 
all  would  be  able  to  tell  you  something  concerning  building 
materials,  cements,  methods  of  construction,  and  would 
recognize  good  work  in  any  of  these  lines,  but  few  know 
the  composition  or  properties  of  paints  used  to  give  the 


4  ANALYSIS  OF  MIXED  PAINTS. 

finishing  coat  and  proper  protection  to  the  walls  of  our 
homes.  Only  a  limited  number  would  be  able  to  intelli- 
gently criticise  the  work.  That  some  paints  wear  well, 
some  crack  or  aligator,  others  peel  and  some  blister,  while 
others  chalk,  is  generally  recalled,  but  the  reason  for  this 
is  not  considered.  The  average  property  owner  from  the 
East  will  tell  you  that  the  paint  on  buildings  does  not  wear 
like  it  formerly  did,  and  they  wonder  why.  Is  it,  they 
say,  because  of  the  inferior  quality  of  the  white  lead  used 
at  the  present  time,  or  because  of  poor  workmanship? 
They  do  not  consider  that  there  are  many  other  factors 
which  may  have  entered  in  as  a  cause  for  present  existing 
conditions,  among  which  may  be  mentioned,  the  inferior 
character  of  some  of  the  wood  now  employed  for  sidings; 
the  condition  of  the  wood  at  the  time  the  paint  is  applied 
which  may  be  unfit  to  receive  the  coat  of  paint.  Or  it  may 
be  due  to  the  character  of  the  priming  coat  which  was  of 
inferior  quality,  perhaps  a  low  grade  of  ochre,  wholly  unfit 
to  be  used  as  a  primer.  Even  the  character  of  the  oil  not 
properly  ripened,  etc.,  may  be  a  determining  agent.  It 
may  be  due  in  part  to  the  physical  condition  of  the  paint, 
for  it  is  a  well-known  fact  that  there  are  now  on  the  market 
numerous  paints,  the  physical  condition  of  which  cannot 
be  commended,  certainly  not  if,  as  has  been  claimed,  that 
fineness  is  an  essential  for  good  wearing  quality.  More 
often  it  is  due  to  the  character  and  condition  of  the  adul- 
terants which  are  added  to  the  paint,  for  it  cannot  be 
denied  but  what  some  of  the  products  in  the  proportion 
in  which  they  are  added,  whatever  their  individual  merits 
may  be,  can  only  be  looked  upon  as  adulterants.  Or  it 
may  be  due  to  the  presence  of  an  excessive  amount  of  water 
used  in  the  paint,  for  many  of  the  paints  which  have  been 
sent  out  of  late  years  have  contained  unnatural  proportions 
of  water,  —  not  intended  to  add  value  to  the  paint,  or  to 


READY  MIXED  PAINTS.  5 

serve  for  preventing  its  settling  and  hardening.  Not  more 
than  from  one  to  two  per  cent  of  water  is  needed,  if  at  all 
necessary,  for  this  purpose.  It  is  not  uncommon  for 
paints  to  contain  from  ten  to  twenty-four  per  cent  of  water 
in  the  liquid  portion.  This,  with  the  small  amount  of 
added  alkalies  and  jelly-like  constituents,  has  produced 
serious  results  for  the  paint  consumer.  Excessive  quan- 
tities of  benzine,  kerosene,  gasoline,  and  various  other 
thinning  vehicles  have  likewise,  been  a  source  of 
trouble. 

What  is  needed  first  of  all,  is  a  better  acquaintance  with 
the  whole  question  of  paint  manufacture  and  use.  The 
first  essential  is  that  the  public  should  become  acquainted 
with  the  chemical  composition  of  paints:  having  made 
themselves  acquainted  with  their  composition,  they  will 
then  know  whether  the  products  purchased  are  what  they 
are  represented  to  be.  They  will  then  need  to  become 
familiar  with  the  physical  properties  of  paints,  and  their 
working  qualities  under  the  brush.  This  will  then  natu- 
rally lead  to  a  study  of  paints  upon  buildings,  and  the 
public  will  become  familiar  with  their  wearing  qualities; 
thus  they  will  be  able  to  understand  some  of  the  causes 
which  lead  to  the  deterioration  of  paints,  and  they  will 
then  demand  products  of  far  better  quality  than  much  of 
that  which  has  been  sent  into  the  state  in  the  past,  even  by 
some  well-known  firms. 

It  is  true  that  competition  has  forced  honest  manufac- 
turers to  lower  their  standards  so  that  they  are  producing 
paint  not  as  good  as  they  know  how  to  produce,  but  as 
good  as  the  general  public  are  willing  to  pay  for  in  the 
face  of  existing  competition  with  unscrupulous  manufac- 
turers and  catalog  house  goods,  which  have  fast  forced 
down  the  standard  of  products  in  all  lines  handled  by 
department  stores  and  run  as  money-making  ventures. 


6  ANALYSIS  OF  MIXED  PAINTS. 

North  Dakota  was  the  first  state  to  enact  any  compre- 
hensive measure  affording  protection  to  the  public  against 
abuses  not  uncommon  during  the  past  few  years. 

The  essential  features  of  the  North  Dakota  paint  law 
are  found  in  Section  1,  which  reads  as  follows: 

"  SECTION  1.  Ever}7  person,  firm  or  corporation  who 
manufactures  for  sale  or  exposes  for  sale,  or  sells  within 
this  state,  any  white  lead,  paint  or  compound  intended 
for  use  as  such,  shall  label  the  same  in  clear  and  distinct 
gothic  letters  upon  a  white  background  and  show  the  true 
per  cent  of  each  mineral  constituent  contained  in  said 
paint,  or  if  other  than  linseed  oil  is  used  in  its  preparation, 
the  names  of  such  oils  or  substitutes  shall  be  shown  together 
with  the  percentage  thereof,  and  every  person,  firm,  or 
corporation  who  manufactures  for  sale  or  exposes  for  sale, 
or  sells  within  this  state  any  mixed  paint  or  compound 
intended  for  use  as  such,  which  contains  any  ingredients 
other  than  pure  linseed  oil,  pure  carbonate  of  lead,  oxide 
of  zinc,  turpentine,  Japan  drier  and  pure  colors,  shall  be 
deemed  guilty  of  a  misdemeanor,  and  upon  conviction 
thereof  shall,  for  each  offence,  be  punished  by  a  fine  of  not 
less  than  twenty-five  and  not  more  than  one  hundred  dol- 
lars and  costs,  or  by  imprisonment  in  the  county  jail  not 
exceeding  sixty  days;  provided,  that  any  such  person,  firm 
or  corporation  who  shall  manufacture  for  sale  or  expose 
for  sale,  or  sell  within  this  state  any  white  lead,  paint  or 
mixed  paint  containing  ingredients  other  than  those  as 
above  enumerated,  shall  not  be  deemed  guilty  of  a  viola- 
tion of  this  act  in  case  the  same  be  properly  labelled,  show- 
ing the  quantity  or  amount  of  each  and  every  ingredient 
used  therein  and  not  specified  above,  and  the  name  and 
residence  of  the  manufacturer  or  person  for  whom  it  is 
manufactured." 

Like  many  first  laws  there  is  considerable  ambiguity 


READY  MIXED  PAINTS.  7 

and  an  opportunity  for  misinterpretation  of  the  spirit  of 
the  law.  It  is  true  also  that  the  measure  has  been  attacked 
on  the  ground  of  unconstitutionally,  and  a  decision  has 
not  as  yet  been  reached  by  the  highest  court  in  the  land, 
and  cannot  be  for  some  months  yet,  although  the  consti- 
tutionality of  the  act  has  been  affirmed  by  the  United 
States  District  Court  for  North  Dakota. 

The  North  Dakota  law  does  not  require  paints  made 
wholly  from  commercially  pure  white  lead,  zinc  oxide, 
linseed  oil,  turpentine,  Japan  drier,  and  pure  colors,  to 
be  labelled.  All  other  paints  must  be  labelled  so  as  to  show 
their  true  composition. 

There  has  been  a  difference  of  opinion  as  to  whether  a 
law  regulating  the  sale  of  paints  should  require  all  paints 
to  be  labelled,  or  only  those  which  have  departed  from  the 
constituents  which  have  been  long  recognized  as  the  basis 
for  paint  manufacture.  Many  arguments  have  been  put 
forth  to  show  that  a  law  exempting  any  paints  is  unfair, 
but  the  evidence  thus  far  presented  has  not  been  sufficient 
to  show  that  it  would  be  desirable  at  this  time  to  recom- 
mend any  change  in  this  direction.  It  is  true  that  all  of 
the  so-called  inert  materials  have  been  used  and  are  still 
used  to  some  extent  in  the  various  mixed  paints,  but  the 
paints  containing  these  constituents  have  generally  been 
represented  as  being  produced  wholly  from  the  con- 
stituents recognized  as  statutory,  and  thus  the  manufac- 
turers have  themselves  made  this  natural  and  distinctive 
classification  which  has  been  adopted  in  the  North  Dakota 
law. 

The  pigments  which  have  been  used  as  substitutes  are 
divided  into  two  groups.  The  first  group  includes  chalk, 
mineral  white,  barytes  (natural  or  artificial),  gypsum, 
silicates,  calcium  carbonates  under  various  names,  as 
Spanish  white,  English  white,  marble  dust,  Paris  white, 


8  ANALYSIS  OF  MIXED  PAINTS. 

whiting,  etc.;  magnesia  compounds,  and  various  alumina 
products,  as,  for  example,  China  clay. 

The  second  group  includes  sublimed  lead,  lithopone, 
leaded  zinc,  and  zinc  lead  white. 

It  may  be  conceded  that  products  of  the  first  group  are 
possessed  of  merit  for  certain  purposes,  yet  they  have  been 
most  generally  employed  as  adulterants,  and  are  found, 
possessed  of  inferior  quality,  to  the  greatest  extent  in  low 
grade  paints,  or  as  adulterants  for  white  lead.  They  are 
cheap,  therefore  lend  themselves  to  misuse. 

It  is  not  generally  claimed  that  they  are  substitutes  for 
white  lead  in  oil,  but  rather  that  they  can  be  used  in  com- 
bination with  white  lead  within  certain  limits  and,  at  times, 
with  advantage.  There  is,  however,  no  general  and  fixed 
consensus  of  opinion  among  paint  manufacturers  or  their 
chemists  as  to  which  of  these  are  best,  —  some  manufac- 
turers condemning  one  and  extolling  the  merits  of  another, 
while  a  competitor  will  as  vigorously  contend  that  the 
reverse  is  true. 

The  physical  condition  of  the  pigment  is  often  a  con- 
trolling factor,  for  it  is  now  well  recognized  that  fineness 
of  subdivision  of  pigment  is  of  vast  importance.  Again, 
not  all  of  the  products  sold  under  a  given  name  are  of  like 
value,  or  even  of  like  chemical  composition.  This  is  well 
shown  in  the  case  of  gypsum,  much  of  the  Western  gypsum 
being  of  inferior  quality  and  not  the  equal  of  certain  East- 
ern products.  If  the  gypsum  is  not  properly  dehydrated 
then,  in  the  presence  of  moisture  as  found  in  paints,  a 
serious  difficulty  arises.  Or  if  lime  carbonate  be  present 
then  by  the  dehydration  of  the  gypsum  quicklime  is  pro- 
duced and  causes  complications.  It  has  been  asserted  also 
that  lime  carbonate  is  desirable  to  counteract  any  acid 
properties  in  the  oil,  but  it  may  be  asked  why  will  not 
the  white  lead  or  even  zinc  oxide  serve  the  same  purpose? 


READY  MIXED  PAINTS.  9 

Such  arguments  seem  futile,  and  certainly  if  any  advantage 
is  to  accrue  from  the  use  of  chalk  or  marble  dust  over  that 
of  lead  or  zinc,  not  to  exceed  two  per  cent  would  be  required 
and  the  necessity  for  the  presence  of  any  great  amount  of 
a  neutralizing  agent  at  once  raises  a  doubt  as  to  the  value 
of  the  linseed  oil,  —  that  is,  as  to  its  freedom  from  oil  pro- 
duced from  foreign  seed,  and  to  its  proper  aging,  or,  if 
boiled  oil,  its  method  of  preparation. 

With  the  present  confusion  and  lack  of  unanimity  among 
paint  chemists  and  manufacturers  as  to  the  relative  merits 
of  the  constituents  and  the  very  general  belief  that  the 
pigments  of  group  one  are  largely  employed  as  cheapening 
agents,  and  not  always  to  the  advantage  of  the  purchaser, 
we  may  dismiss  for  the  present  any  consideration  of  their 
being  the  equal  of  the  statutory  pigments  in  ready  mixed 
house  paints;  at  least  until  such  time  as  their  true  worth 
has  been  demonstrated  through  a  rigid  and  comprehensive 
series  of  practical  paint  tests  checked  up  by  appropriate 
chemical  and  physical  examinations.  It  will  also  be  nec- 
essary to  determine  to  what  extent,  if  any,  they  can  replace 
white  lead,  or  should  tthe  proportion  of  white  lead  remain 
the  same  and  they  be  used  as  a  substitute  for  the  zinc 
oxide. 

It  should  not  be  understood,  however,  that  these  pro- 
ducts when  properly  used  are  to  be  classed  as  adulterants, 
for  this  term  is  being  abused  and  misused.  For  example, 
in  lithopone,  barium  sulphate  is  a  recognized  component, 
and  when  lithopone  is  used  as  such  it  is  a  perfectly 
legitimate  product.  The  same  is  true  of  many  other  pig- 
ments. 

With  regard  to  the  members  of  group  two,  some  discus- 
sion of  the  several  pigments  will  not,  at  this  time,  be 
inappropriate. 

Sublimed    lead.    Sublimed    lead     sulphate,    sometimes 


10  ANALYSIS  OF  MIXED  PAINTS. 

called  the  oxy-sulphate,  or  the  basic  sulphate,  seems  to 
have  had  many  ups  and  downs  in  its  short  history. 

It  was  first  put  upon  the  market  commercially  about 
twenty-five  years  ago  and,  according  to  Hurst,  its  compo- 
sition was  very  variable,  much  depending  upon  the  char- 
acter of  the  low  grade  ores  from  which  it  was  produced, 
the  temperature  in  the  furnace,  and  the  proportion  of  air 
which  came  in  contact  with  the  ore.  Writing  as  late  as 
1901,  Hurst  reaffirms  his  former  statement  with  regard  to 
its  variable  composition.  Many  of  the  manufacturing 
obstacles  have,  however,  been  largely  overcome  in  the 
last  few  years,  especially  in  America,  and  the  product  is 
now  tolerably  uniform,  and  in  the  purest  form  seems  to 
average  in  composition  about: 

Per  cent. 

Lead  sulphate 75 

Lead  oxide 20 

Zinc  oxide 5    - 

100 

The  pigment  is  very  fine,  possessing  good  covering  power, 
but  in  use  is  not  always  satisfactory.  Sublimed  lead 
seems  to  differ  in  many  ways  from  the  simple  physical 
mixture  of  lead  sulphate,  lead  oxide,  and  zinc  oxide.  The 
claim  that  it  is  the  basic  sulphate,  or  the  oxy-sulphate, 
seems,  however,  not  to  have  been  properly  verified  at  the 
present  writing.  It  seems  to  be  rather  a  complex  mixture 
of  several  of  these  constituents.  That  it  should  differ 
from  a  mechanical  mixture  of  the  above-named  pigments, 
may  be  due  in  part  to  the  greater  degree  of  fineness  and 
more  complete  intermixture  in  the  process  of  sublimation. 

The  use  of  sublimed  lead  has  greatly  increased  during 
the  past  few  years,  and  an  increased  number  of  manu- 
facturers are  now  using  sublimed  lead  to  some  extent. 
In  the  preparation  of  mixed  paints  the  firms  adopting  its 


READY  MIXED  PAINTS.  11 

use  to  the  largest  extent  during  the  past  two  years,  judg- 
ing from  the  paints  sold  in  North  Dakota,  are  the  ones 
least  equipped  for  conducting  experimental  work  under 
the  guidance  of  a  trained  chemist. 

Several  firms  report  having  in  years  past  tried  the 
product  with  unsatisfactory  results,  and  have  discon- 
tinued its  use  in  their  regular  lines  of  mixed  paints.  Firms 
who  have  been  using  sublimed  lead  in  their  darker  shades 
have  not  generally  adopted  its  use  in  the  whites.  How- 
ever, in  one  instance  when  used  with  a  white  this  yellow  tint 
was  corrected  by  the  addition  of  a  slight  amount  of  blue. 

For  example,  a  gray  and  an  outside  white  as  examined 
gave  for  the  essential  constituents  approximately  as 
follows : 

White.  Gray. 

White  lead 59.00  9.00 

Lead  sulphate 2.00  45.00 

Zinc  oxide      34 . 00  44 . 00 

There  has  been  considerable  complaint  regarding  the 
working  qualities  of  sublimed  lead  paints.  In  a  test  made 
by  using  sublimed  lead  ground  in  oil  and  with  great  care 
to  prevent  heating,  it  was  found  that  during  the  cool  part 
of  the  day,  in  the  morning  and  evening,  the  paint  was 
spread  and  brushed  out  with  considerable  difficulty. 
Others  have  reported  like  experiences.  In  a  more  recent 
test,  where  a  mixed  paint  composed  of  60  per  cent  of 
sublimed  lead  and  40  per  cent  of  zinc  oxide  was  under 
test,  considerable  difficulty  was  experienced  toward  even- 
ing as  the  day  became  cooler,  although  all  the  other  condi- 
tions were  most  favorable  for  painting. 

In  the  past  there  has  been  produced  a  large  number  of 
paints  of  rather  inferior  quality,  so  far  as  composition  is 
concerned,  made  up  largely  of  so-called  inert  material: 
chalk,  barytes,  clays,  silicates,  water,  etc.,  and  it  is  notice- 


12  ANALYSIS  OF  MIXED  PAINTS. 

able  that  during  the  past  two  years,  or  since  the  enforce- 
ment of  the  North  Dakota  law,  several  of  these  firms 
have  been  endeavoring  to  improve  somewhat  the  quality 
of  their  paint,  and  are  substituting  sublimed  lead  or  lead 
sulphate,  but  even  in  the  best  grades  of  these  paints,  as 
examined  in  this  laboratory,  it  has  been  found  that  the 
lead  sulphate  is  generally  used  in  combination  with  other 
products  and  particularly  with  white  lead  proper,  and 
not  alone  or  with  zinc  oxide  only. 

An  example  of  the  change  made  in  one  case  is  clearly 
shown  by  comparison  of  an  outside  white  as  produced 
one  year  ago,  with  that  produced  by  the  same  firm  at  the 
present  time : 

Old.  New. 

Lead  sulphate 0 . 00  20 . 00 

Zinc  oxide      53.00  43.00 

Calcium  carbonate 46 . 00  26 . 00 

Silica 11.00 

For  the  new  product,  it  is  claimed  on  the  label  that  the 
formula  is: 

Per  cent. 

Zinc  white 55 

Lead  white 45 

100 

This  is  not  at  all  what  the  analysis  shows  it  to  be. 
In  the  case  of  another  sample  of  paint  recently  exam- 
ined we  find  the  proportion  to  be : 

Per  cent 

White  lead 23 

Lead  sulphate 19 

Lead  oxide 6 

Zinc  oxide 26 

Barium  sulphate 22 

Other  constituents 4 

100 


READY  MIXED  PAINTS.  13 

A  mixed  paint  to  be  satisfactory  must  not  be  too  slow 
in  drying,  otherwise  showers,  dust  storms,  and  myriads 
of  insects  deface  it  and  give  an  unsatisfactory  surface. 
The  tendency  for  a  paint  to  become  gelatinous  is  also  an 
unfortunate  condition  at  times  met  with.  These  last 
named  properties  have  been  objections  strongly  urged 
against  the  use  of  sublimed  lead.  When  used  in  connec- 
tion with  considerable  proportions  of  white  lead,  zinc 
oxide,  and  diluting  materials,  or  inert  pigments,  it  is  pos- 
sible that  sublimed  lead  may  give  satisfactory  results,  and 
this  would  seem  to  be  true  since  we  have  found  its  use 
more  general  under  these  conditions,  also  in  cases  where 
permanent  whiteness  is  not  such  an  important  matter. 
From  personal  knowledge  the  writer  would  say  that  sub- 
limed lead  is  better  adapted  for  use  in  paints  for  farm 
machinery,  where  dipping  is  resorted  to  rather  than 
brushing. 

Lithopone.  Lithopone  is  now  a  fairly  uniform  product, 
quite  generally  used  in  the  preparation  of  the  cheaper 
enamels,  in  oil  cloth,  and  floor  cloth  industries  and,  to 
some  extent,  in  floor  paints,  but  it  has  not,  as  yet,  been 
used  to  any  great  extent  in  mixed  paints.  From  its 
nature  it  cannot  be  used  in  paints  under  certain  conditions 
with  any  degree  of  satisfaction,  and,  therefore,  the  pur- 
chaser should  know  of  its  presence  in  order  that  he  may 
avoid  such  difficulties.  Aside  from  any  objectionable 
features  it  is  probable  that  the  demand  for  lithopone  for 
other  purposes  will  be  such  as  to  prevent  its  being  gener- 
ally employed,  for  some  time  at  least,  in  the  preparation 
of  mixed  paints  except  in  certain  specialties. 

Leaded  zincs.  Leaded  zincs  show  considerable  varia- 
tion as  now  found  upon  the  market.  The  New  Jersey 
zinc  produced  from  Franklinite  is  practically  99  per  cent 
or  more  zinc  oxide,  and  seldom  contains  more  than  a  trace 


14  ANALYSIS  OF  MIXED  PAINTS. 

of  lead.  On  the  other  hand,  the  Mineral  Point  zinc  con- 
tains varying  amounts  of  lead  sulphate,  and  above  all 
zinc  sulphate  which  is  recognized  as  an  objectionable 
feature  when  present  in  any  considerable  quantity. 

There  would  seem  to  be  three  grades  of  Mineral  Point 
zinc  products,  the  purest  of  which  contains  from  three  to 
four  per  cent  of  lead  sulphate. 

The  leaded  zincs  from  the  Missouri  and  Kansas  fields 
show  an  extremely  wide  range  in  composition,  containing 
from  four  to  twenty-five  per  cent  of  lead  sulphate,  and, 
at  times,  as  high  as  one  and  a  half  per  cent  of  zinc  sul- 
phate. It  also  at  times  contains  as  high  as  one-half  per 
cent  of  SO  2  which  in  some  instances  in  paint  manufacture 
has  been  a  source  of  great  trouble,  resulting  in  heavy  loss 
and  in  the  production  of  a  paint  not  usable. 

With  regard  to  zinc  sulphate,  Hughes  says:  "  Zinc 
sulphate,  an  almost  invariable  ingredient  of  leaded  zinc, 
and  zinc  oxide  made  from  sulphides  sometimes  causes 
startling  changes  for  which  the  painter  usually  is  blamed.'7 

In  the  light  of  present  experience,  therefore,  zinc  sul- 
phate in  such  quantities  cannot  be  looked  upon  other  than 
with  some  degree  of  suspicion  in  mixed  paints,  although 
Toch  does  not  consider  it  harmful  to  the  extent  that  has 
been  generally  claimed. 

It  would  seem,  therefore,  that  before  one  is  justified  in 
assuming  the  presence  of  zinc  sulphate  as  without  preju- 
dicial influence,  it  will  be  necessary  to  conduct  investiga- 
tions in  practical  tests  to  determine  under  what  condi- 
tions, if  any,  it  can  be  safely  allowed  in  paints,  and  to 
what  extent. 

Zinc  lead  whites.  Zinc  lead  white  is  largely  a  product 
from  Colorado  low  grade  ores,  —  a  mixture  of  zinc  oxide 
and  lead  sulphate  very  intimately  combined  at  the  high 
temperatures  at  which  these  products  are  volatilized,  and 


READY   MIXED   PAINTS.  15 

t 
then  arc  oxidized  in  appropriate  chambers.     Only  during 

the  past  five  years  has  there  been  attained  anything  like 
uniformity  in  composition  and,  even  at  the  present  time, 
as  shown  under  the  analyses  of  zinc  lead  whites  by  Pro- 
fessor Holley,  they  have  been  found  to  contain  the  follow- 
ing range  for  arsenic,  antimony  compounds,  and  zinc 
sulphate : 

I  II  III  IV 

Per  cent.  Per  cent.  Per  cent.    Per  cent. 

Arsenious  oxide 68  .47  .32  1.60 

Antimony  oxide 20  .33  .20  .88 

Zinc  sulphate 78  .55  1.61  .84 

In  other  words  there  may  be  present  as  much  as  three 
and  one-half  per  cent  of  these  objectionable  constituents. 
The  writer  seriously  questions  whether  the  presence  in 
these  proportions  of  such  constituents  does  not  very 
materially  detract  from  the  good  quality  of  paint.  Cer- 
tainly arsenic  and  antimony  compounds  are  not  more 
desirable  for  interior  paints  than  are  the  arsenic  com- 
pounds desirable  in  our  wall  papers,  the  presence  of  which 
in  wall  paper  in  the  past  has  proven  such  a  menace  to 
health. 

The  writer  cannot  do  other  than  maintain  that  when 
any  of  the  foregoing  pigments  are  used  in  place  of  the 
long  recognized  statutory  pigments,  the  public  have  a 
right  to  know  of  their  presence,  and  they  are  not  to  be 
classed  as  possessed  of  the  same  degree  of  merit  for  paint 
production  as  are  the  statutory  pigments.  At  least  it 
cannot  be  claimed  that  experience  has,  as  yet,  demon- 
strated their  like  worth.  Further,  the  fact  that  the 
manufacturer  of  those  pigments  is  constantly  striving  to 
eliminate  certain  constituents;  adopting  new  devices  in 
manufacture,  and  bringing  out  new  products  and  pre- 
sumably better  than  that  previously  produced,  is  indicative 


16  ANALYSIS   OF   MIXED   PAINTS. 

of  needs  for  further  improvements  and  clearly  indicates 
an  unsettled  condition. 

If  there  are  standards  recognized  for  food  products,  for 
drugs,  for  beverages,  such  as  whiskey,  for  commercial 
fertilizers,  etc.,  why  should  not  like  standards,  generally 
recognized  from  their  long  and  favorable  use,  be  accepted 
as  a  basis  for  paints  of  high  quality  ?  Any  attempt,  there- 
fore, to  secure  legislation  requiring  all  paints  to  be  labelled 
under  like  conditions  is  an  attempt  to  place  all  constituents 
entering  into  the  composition  of  paints  on  a  like  footing. 
Every  honest  paint  manufacturer  knows  that  such  claim 
is  not  true. 

In  dealing  with  this  question  the  writer  would  have  it 
understood,  of  course,  that  his  reference  has  been  to  that 
class  of  mixed  paints  used  as  house  paints,  and  not  those 
special  paints  prepared  for  use  upon  structural  steel,  for 
lighthouse  purposes,  or  even  upon  railway  cars,  where 
conditions  are  quite  different,  and  where,  as  a  rule,  expert 
chemists  are  employed  to  see  that  the  products  furnished 
are  in  compliance  with  previously  prepared  specifications, 
none  of  which  conditions  pertain  to  paints  as  ordinarily 
met  with  in  commerce.  Otherwise,  who  is  to  safeguard 
the  consumer  against  such  abuses,  or  how  is  the  producer 
of  honest  paints  to  have  proper  protection? 

Under  the  North  Dakota  law  it  is  required,  where  con- 
stituents other  than  statutory  ones  are  employed,  that  the 
paint  shall  be  labelled  to  show  the  composition  of  the  same, 
and  the  form  which  presents  this  information  most  satis- 
factorily for  the  public,  it  seems  to  the  writer,  is  the  one 
adopted  in  reporting  the  analyses  made  at  the  North 
Dakota  Experiment  Station,  and  is  as  follows: 


.  i,  \^>v> 

^'     OF  THE      " 

UNIVERSITY 


^~  YDY   MIXED   PAINTS.  17 


FORM   FOR   LABEL. 

Contents  of  can gal.     Ibs. 

Per  cent  of  pigment,  by  weight        62 

Per  cent  of  thinner  or  vehicle  by  weight 38 

100 

The  thinner  or  vehicle  is  composed  of: 

Per  cent. 

Linseed  oil 70 

Turpentine 5 

Japan  drier      

Benzine 10 

Water 10 

100 

Composition  of  pigment: 

Per  cent. 

White  lead 25 

Sublimed  lead 20 

Zinc  oxide 30 

Calcium  carbonate 6 

Barytes 15 

Color1 4 

100 

This  should  be  followed  or  preceded  by  the  name  of 
the  manufacturer  and  his  address.  This  does  not  preclude 
however,  the  use  also  of  the  name  of  the  jobber  on  the 
same  label  if  it  is  desired. 

Where  water  is  present  not  to  exceed  1.5  per  cent  of 
the  fluid  portion  it  is  considered  as  incidental.  Or  where 
Western  zincs  are  employed  and  carry  not  to  exceed 
5  per  cent  of  lead  sulphate,  and  are  free  from  other  in- 
jurious impurities,  the  products  are  considered  as  com- 
mercially pure  and  labelling  is  not  necessary,  provided  all 
other  conditions  are  in  compliance  with  the  requirements 
of  the  law. 

1  The  color  is  composed  of:  (name  of  ingredients  and  composition 
when  necessary  to  be  given.) 


18  ANALYSIS   OF   MIXED   PAINTS. 

Where  coloring  matter  is  used  to  secure  the  desired 
tint,  it  is  assumed  that  this  coloring  matter  is  commercially 
pure,  but  where  the  coloring  matter  is  of  such  a  character 
as  to  require  an  unusual  amount  of  color,  then  the  product 
should  not  be  deemed  as  properly  labelled  unless  the 
analysis  of  this  color  be  given.  It  is  a  well-known  fact 
that  some  of  the  ochres  are  of  such  inferior  quality  that 
not  less  than  20  per  cent  of  the  color  may  be  used  as  pig- 
ment, and  not  more  than  8  or  10  per  cent  of  this  should 
properly  be  classed  as  real  color,  and  the  other  constituents 
enumerated  as  dilutants. 

The  question  may  be  raised  as  to  the  reasons  for  label- 
ling as  indicated  in  the  foregoing.  It  will  be  observed  in 
the  study  of  paints  that  the  manufacturer  who  uses  the 
largest  amount  of  cheap,  inferior  pigments  will  employ  the 
least  amount  of  oil,  for  when  calculated  according  to  vol- 
ume, oil  is  more  expensive  than  some  of  the  pigments. 
He,  therefore,  adds  water  and  recommends  that  the  con- 
sumer add  the  necessary  oil  and  turpentine  to  thin  the 
same  for  use.  On  the  other  hand,  the  manufacturer  pro- 
ducing the  highest  grade  of  paints  tries  to  combine  pig- 
ment and  vehicle  in  such  proportion  that  they  are  ready 
for  use ;  but  linseed  oil  is  cheaper  than  white  lead,  and, 
therefore,  some  paint  manufacturers  employ  as  large  a 
per  cent  of  oil  as  can  well  be  used,  and  advertise  the  great 
spreading  power  of  their  paints. 

It  is  thus  important  that  we  have  full  measure  or  weight, 
and  proper  information  with  regard  to  the  proportion 
by  weight  of  pigment  and  thinner. 

By  separating  the  thinner  or  vehicle  from  the  pigment, 
the  facts  are  most  clearly  indicated  to  the  untrained 
mind,  for  example,  the  proportion  of  water;  for  instance, 
ten  pounds  in  every  hundred  of  the  liquid  portion.  Or 
in  the  pigment  thirty  pounds  of  chalk  or  marble  dust  or 


READY   MIXED   PAINTS.  19 

barytes  to  each  hundred  pounds.  Where  the  pigment  and 
vehicle  are  combined  the  relative  proportion  of  barytes, 
benzine,  water,  etc.,  is  made  to  appear  considerably  less 
than  where  they  are  calculated  on  the  actual  amount  of 
thinner  employed,  and  this  to  the  advantage  of  the  manu- 
facturer. 

To  make  a  statement  for  the  express  purpose  of  mis- 
leading, is  as  much  a  falsehood  as  to  deliberately  tell  a  lie, 
and  indicates  that  there  is  back  of  it,  one  not  wholly  to 
be  relied  upon  in  matters  upon  which  he  should  be  an 
authority. 

To  say  that  the  lead  and  zinc  in  the  paint  are  "guaranteed 
to  be  strictly  pure/'  when  they  constitute  but  part  of  the 
pigment,  is  to  perpetrate  a  fraud,  and  to  deliberately 
falsif}^  Yet  this  is  not  an  uncommon  practice  in  regard 
to  paint  literature  furnished  by  manufacturers.  Or,  if 
not  found  in  the  literature,  it  is  spoken  by  the  salesman 
who  represents  the  product. 

Take  this  statement:  "This  mixed  paint  contains  the 
proper  proportion  of  zinc.  It  is  a  lead,  zinc,  and  oil 
paint  —  the  real  thing."  Is  this  a  truthful  statement 

when  the  composition  is : 

Per  cent. 

White  lead 25 

Lead  sulphate 25 

Zinc  oxide 25 

Barytes    .    .    . 25 

100 

No  honest  manufacturer  of  paints  should  make  a  state- 
ment like  the  foregoing,  or  allow  his  salesmen  to  mis- 
represent facts.  And  yet  if  you  are  to  eliminate  all  as 
friends  who  follow  such  a  course,  there  would  remain  but 
few  manufacturers  for  one  to  associate  with.  Such  ingen- 
ious statements  do  not  give  one  a  good  opinion  of  busi- 
ness men  engaged  in  the  manufacture  of  paints,  and  if 


20  ANALYSIS   OF  MIXED   PAINTS. 

their  word  is  questioned  on  paint  matters  they  have  no 
just  reason  for  resenting  it,  until  such  time  as  paint  litera- 
ture is  properly  revised.  Commercial  practise  rather  than 
inherent  dishonesty  is  at  fault,  for  much  of  this  unfortu- 
nate condition,  also  lack,  on  the  part  of  some  manufac- 
turers, of  moral  courage  to  lead  in  a  crusade  for  honest 
labelling.  Time  and  forced  changes  must  soon  remedy 
this  condition. 

Here  is  another  example  of  fraud,  —  where  the  manu- 
facturer labels  his  product  as  "  white  lead  "  and  says: 
"  We  guarantee  our  white  lead  to  be  superior  to  any  white 
lead  on  the  market  as  regards  opacity  or  body-covering 
capacity.  It  is  also  extremely  durable,  possessing  in  this 
particular  great  merit.  For  whiteness  and  fineness  of 
texture  it  will  be  found  unsurpassed."  Now  he  has  told 
but  a  small  part  of  the  real  truth. 

Now  the  public  are  justified  in  believing  that  this  pro- 
duct is  the  equal  of  any  white  lead  upon  the  market.  In 
fact,  that  it  is  chemically  pure  white  lead.  The  analysis 
shows  the  pigment  to  contain : 

Per  cent. 

White  lead 37.51 

Lead  sulphate 7 . 84 

Zinc  oxide      25 . 87 

Calcium  carbonate 20 . 36 

Barytes,  silica,  and  undetermined 8 . 42 

100.00 

Another  product  labelled  as  white  lead  was  found  to 
contain  90  per  cent  of  barytes,  and  no  white  lead  at  all. 

Now  such  claims  as  the  foregoing  are  intentionally  mis- 
leading and  false,  are  given  out  solely  for  the  purpose  of 
deceiving  the  public,  and  inducing  them  to  purchase  these 
products  at  exorbitant  prices.  These  products  usually 
retail  at  about  the  same  price  as  does  genuine  Old  Process 
Dutch  White  Lead,  and  it  is  to  secure  this  unwarranted 
advantage  that  many  of  these  products  are  so  advertised. 


READY  MIXED   PAINTS.  21 

As  showing  the  need  of:  a  law  to  prevent  fraud  in  paints 
we  may  cite  a  few  examples.  We  give  three  analyses  of 
products  sold  as  white  lead  and  usually  at  approximately 
the  same  prices  per  pound  as  received  for  Old  Process 
Dutch  White  Lead. 


White  lead  
Lead  sulphate  .... 
Zinc  oxide  

No.  1. 
00 
.     20 
20 

No.  2. 
00 
5 
25 

No.  3. 
39 
5 
34 

Calcium  carbonate  .  . 
Barvtes  . 

8 
52 

70 

19 
3 

Many  manufacturers  dwell  much  upon  the  importance 
of  having  pure  linseed  oil  and  turpentine,  and  maintain 
that  the  life  of  the  pain1<  is  largely  dependent  upon  the 
linseed  oil.  Some  of  the  paints  found  upon  the  market 
in  North  Dakota  at  the  time  the  law  went  into  force, 
clearly  shows  a  kind  of  "doping  "  not  at  all  commendable 
or  in  keeping  with  what  the  public  had  a  right  to  presume 
they  were  purchasing. 

We  cite  the  following  examples  as  showing  the  com- 
position of  the  liquid  portion  of  some  of  these  paints. 


Linseed  oil 
Turpentine 
Benzine  .    . 
Water     .    . 

1 
.    .     55 

24 
.    .     21 

2 
69 

ie 

15 

3 
52 

26 
22 

4 
70 
11 

i9 

5 
57 

21 
22 

6 

72 

4 
24 

7 
64 
6 
14 
16 

This  certainly  shows  a  remarkable  condition,  and  one 
which  all  paint  chemists  have  condemned,  and  yet  this 
represents  not  alone  the  low  grade  paints,  but  some  of  the 
products  produced  by  manufacturers  of  the  highest 
standing. 

As  to  the  use  of  water  in  paints,  without  further  com- 
ment we  may  quote  Toch:  "Three  per  cent  is  entirely 
excessive  in  an  exterior  linseed  oil  paint,  and  a  manufac- 
turer has  no  right,  either  morally  or  legally,  to  hide  behind 


22  ANALYSIS  OF  MIXED   PAINTS. 

a  misrepresentation  of  his  paint  when  the  paint  is  largely 
adulterated  for  the  purpose  of  overcoming  his  ignorance 
in  the  manufacture." 

That  the  water  further  exerts  an  injurious  effect  is 
also  noted  by  the  same  author,  who  says:  "  Ethics  would 
clearly  indicate  that  no  manufacturer  has  a  moral  right  to 
label  his  paint  as  being  entirely  pure  and  composed  of 
four  materials,  when  as  a  matter  of  fact  an  excessive 
quantity  of  water  was  added  which  destroyed  in  a  large 
degree  the  value  of  the  other  materials." 

On  the  other  hand,  as  showing  about  the  proportion  of 
the  constituents  entering  into  the  fluid  portion  of  some  of 
the  best  made  paints,  we  quote  the  following  example : 

ANALYSIS   OF  THINNER. 


1 

2 

3 

4 

5 

6 

Linseed  oil     ... 

.    .     93 

91 

86 

95 

90 

94 

Turpentine  drier  . 

.    .       7 

9 

14 

5 

10 

6 

Water     

.    .       0 

0 

0 

0 

0 

Benzine  

.    .       0 

0 

0 

0 

0 

0 

In  the  best  prepared  paints  we  have  usually  found 
from  4  to  7  per  cent  of  turpentine  drier  in  the  liquid 
portion.  For  a  heavy-bodied  oil  this  seems  to  be  ample. 

Without  entering  into  any  further  discussion  as  to  the 
relative  merits  of  the  various  pigments  we  may  consider  a 
few  cases  where  the  public  were  justified  in  assuming  they 
were  purchasing  a  paint  made  wholly  from  white  lead  and 
zinc  oxide. 

ANALYSIS   OF   PAINT   PIGMENTS. 

123456 

White  lead 00          9  00  00  00  00 

Zinc  oxide      52         44  40  24  47  43 

Calcium  carbonate 46         . .  34  5  . .  26 

Magnesium  carbonate 1 

Barytes 22  66 

Lead  sulphate 45  4  5  .3  19 

Clay  and  silica 2  . .  .  .  49  12 


READY   MIXED   PAINTS.  23 

Without  commenting  on  the  physical  condition  of  these 
several  paints  which  in  some  instances  were  not  at  all 
desirable  we  may  ask:  Is  the  public  not  entitled  to  some 
protection  against  the  sale  of  paints  so  labelled  as  to  give 
the  impression  that  they  are  getting  white  lead  and  zinc 
oxide?  Not  all  of  the  above  paints  are  by  any  means  to 
be  classed  as  catalog  house  paints.  It  is  not  for  one 
moment  to  be  supposed  either,  that  the  paints  are  ideal  in 
composition  or  that  the  honest  paint  manufacturer  so 
considers  them. 

Here  is  a  type  of  a  different  class  of  paints  put  up  in 
dry  form  and  largely  advertised. 

Per  cent. 

Moisture  and  combined  water 5 . 74 

Casein 14.59 

Ferric  oxide 19.26 

Soluble  alumina 1 . 24 

Gypsum 21.53 

Lime 7.60 

Magnesium  silicate 30.04 


100.00 

The  constituents  other  than  casein  in  this  costs  about  one 
cent  per  pound,  and  it  is  a  good  example  of  what  might 
properly  be  classed  as  a  "  fake  "  paint. 

If  a  cheap  paint  is  desired  it  is  better  to  use  a  good  white- 
wash, for  it  would  probably  serve  as  a  protective  coat 
better  than  the  above.  What  is  known  as  the  Govern- 
ment formula  for  whitewash  is  as  follows: 

"  Slack  one-half  bushel  of  lime  with  boiling  water,  keep- 
ing it  covered  during  the  process.  Strain  it,  add  a  peck  of 
salt  dissolved  in  warm  water;  three  pounds  ground  rice  put 
in  boiling  water  and  boiled  to  a  thin  paste;  one-half  pound 
powdered  Spanish  whiting,  and  a  pound  of  clear  glue  dis- 
solved in  warm  water;  mix  these  well  together  and  let  the 
mixture  stand  for  several  days.  Keep  the  wash  thus  pre- 


24  ANALYSIS   OF  MIXED  PAINTS. 

pared  in  a  kettle  or  portable  furnace,  and,  when  used,  put 
it  on  as  hot  as  possible  with  painter's  or  whitewash  brush." 

Short  measure  and  weights.  Another  feature  quite  com- 
mon is  short  measure  in  mixed  paints  and  short  weight  in 
paste  paints.  In  case  of  white  lead  and  combination  leads 
they  average  10  to  12  per  cent  short  weight,  or  kegs  sold 
for  12J  pounds  will  run  10  to  10J  pounds,  and  25  and 
50  pound  kegs,  respectively,  about  22  and  46  pounds.  All 
weights  should  be  net  as  represented. 

In  the  mixed  paints  they  run  not  infrequently  10  to  13 
per  cent  short  in  measure.  In  two- quart  containers  we 
have  found  them  to  run  as  follows: 


Number.  Quarts. 

1      1.92 

2      1.82 

3      1.76 

4      1.75 

5  1.70 


One  of  the  gallon  containers  purchased  direct  from  the 
producer  actually  contained  3.41  quarts. 

Relation  of  lead  to  zinc.  Much  has  been  said  concerning 
the  fact  that  the  North  Dakota  law  is  silent  regarding  the 
proportion  of  lead  to  zinc  permissible  in  statutory  paints. 
Who  shall  at  the  present  time  say  what  proportion  is  best? 
The  relation  of  lead  to  zinc  for  exterior  work  would  undoubt- 
edly be  different  than  in  paints  intended  for  interior  house 
painting.  The  difference  in  cost  between  the  best  grades 
of  those  two  pigments  is  not  so  great  that  manufacturers 
of  high  grade  paints  will  be  likely  to  cheapen  the  product 
at  the  expense  of  what  to  him  seems  safe  for  the  locality 
where  his  paint  is  most  largely  used.  At  the  present  time 
we  find  that  some  are  using  30  per  cent  of  white  lead  to  70 
of  zinc  oxide.  This  is  the  limit  for  zinc.  Others  employ 
these  in  proportion  of  50  per  cent  for  each,  and  there  are 


READY   MIXED   PAINTS.  25 

now  a  few  using  60  per  cent  of  white  lead  and  40  per  cent 
of  New  Jersey  zinc  oxide. 

There  are  many  practical  painters  who  express  the 
opinion  that  the  proportion  should  be  from  66  to  75  per 
cent  lead,  or  not  more  than  one-fourth  to  one-third  of  the 
pigment  should  be  zinc  oxide,  while  the  advocate  of  white 
lead  would  have  none  of  zinc.  A  few  of  the  white  lead 
advocates  would  use  10  to  25  per  cent  of  zinc  oxide  in  the 
finish  coat.  Experiments  are  necessary  to  determine  in 
what  proportion  these  pigments  shall  be  added  in  order  to 
secure  the  best  results. 

Experience  may  teach  us  that  some  of  the  other  pig- 
ments are  preferable  to  either  of  the  above  named.  If  so, 
we  should  welcome  the  proof  and  prepare  to  adopt  stan- 
dards of  comparison  based  on  such  proof.  The  author  is 
a  believer  in  mixed  paints,  but  maintains  that  when  other 
constituents,  either  as  thinner  or  pigment,  are  introduced 
in  place  of  those  generally  recognized  as  being  present,  this 
fact  should  be  clearly  set  forth  and  that  false  or  exaggerated 
statements  regarding  all  claims  of  paints  should  be  dis- 
countenanced alike  by  the  general  public  and  the  honest 
manufacturer,  who  in  the  past  has  suffered  through  abuses 
of  commercial  methods  based  upon  an  erroneous  idea  of 
the  science  of  right  and  of  right  character  and  conduct  in 
business  affairs.  In  the  end,  in  paint  matters  as  well  as 
elsewhere,  that  which  is  true  and  just  will  prevail. 


PART  II. 


ANALYSIS   OF   PAINTS,   COLORS,   AND 
VARNISHES. 

BY  C.   D.   HOLLEY. 


27 


CHAPTER  I. 

ANALYSIS  OF  MIXED  PAINTS, 

1.  Preparation  of  sample.     If  a  dry  color,  and  in  bulk, 
great  care  must  be  exercised  in  securing  a  uniform  sample 
which  should  be  thoroughly  mixed  on  the  mixing  cloth.     If 
the  sample  be  a  liquid  paint  in  the  unbroken  package,  the 
brand,  manufacturer,  and  guarantee  should  be  carefully 
noted.    The  package  is  then  weighed,  opened,  and  the  con- 
dition and  volume  of  the  contents  noted.     If  the  pigment 
has  settled  hard  in  the  bottom  of  the  can,  pour  off  the  oil 
into  the  mixing  can  and  work  up  the  paste  until  free  from 
lumps,  gradually  adding  the  oil  portion  and  stirring  to  a 
uniform  consistency;  pour  into  the  mixing  can,  scraping 
out  the  contents  of  the  package  thoroughly.     Stir  until 
thoroughly  convinced  that  the  sample  is  uniform  in  com- 
position.   The  entire  success  of  the  analysis  depends  upon 
securing  a  uniform  sample,  and  more  analyses  are  incorrect 
because  of  carelessness  in  the  preparation  of  the  sample  to 
be  analyzed  than  from  any  other  source.     The  volume  and 
weight  of  the  empty  can  are  also  noted. 

2.  Separation  of  the  vehicle  from  the  pigment.     Much 
difficulty  is  often  experienced  in  extracting  the  vehicle  from 
the  pigment,  due  to  the  fineness  of  the  pigment  particles 
and  the  ease  with  which  they  pass  through  the  walls  of  the 
extraction  tubes.    This  difficulty,  however,  may  be  entirely 
avoided  by  the  use  of  the  apparatus  illustrated  below. 
The  extraction  thimble,  containing  a  filter  folded  cylin- 
drically,  is  dried  in  the   hot  water  oven  for    one   hour, 
weighed,  and  10  to  15  grams  of  the  sample  weighed  into  it, 

29 


30  ANALYSIS  OF  MIXED   PAINTS. 

extracted  with  ether  for  24  to  36  hours,  dried  and  weighed 
again.    The  loss  in  weight  represents  the  vehicle,  and  the 


FIG.  2.  —  EXTRACTION  APPARATUS. 

residue  remaining,  the  pigment,  which  is  reduced  to  a  fine 
powder  and  kept  tightly  stoppered  until  examined.    Any 


ANALYSIS  OF  MIXED   PAINTS. 


31 


casein  or  similar  product  in  the  paint  will  remain  unex- 
tracted  by  the  ether,  and  unless  detected  will  interfere 
with  the  proper  analysis  of  the  pigment. 

3.  Ratio  of  pigment   to  vehicle.     It  is  customary  with 
a  large  number  of  manufacturers  to  have  one  ratio  of 
pigment  to  vehicle  for  white   paints,  and   another  ratio 
for  the  tints.     In  some  cases  this  is  necessary.,  owing  to 
the  low  specific  gravity  of  the  tinting  colors;  but  in  many 
instances  where  only  one  or  two  per  cent  of  color  is  added 
to  the  white  base,  it  is  not  necessary  to  reduce  the  propor- 
tion of  pigment,  even  though  such  paints  may  hide  better 
than  the  whites. 

4.  Typical   analyses  of   white   and  gray   paints,   from 
the  same  manufacturers,  showing  the  change  in  the  ratio 
of  pigment  to  vehicle. 


] 

[. 

I 

I. 

II 

[. 

White. 

Lead 
Color. 

White. 

Gray. 

White. 

Gray. 

Pigment      
Vehicle    

65.6 
34.4 

57.2 

42.8 

62.6 
37.4 

54.9 
45.1 

63.2 
36.8 

54.9 
45.1 

Vehicle: 
Linseed  oil      .... 
Drier   
Water  

100.0 

88.9 
9.3 
1.8 

100.0 

89.5 
8.6 
1.9 

100.0 

86.0 
12.6 
1.4 

100.0 

84.7 
13.8 
1.5 

100.0 

97.0 
2.0 
1.0 

100.0 

83.9 
14.9 
1.2 

Pigment  : 
White  lead     .... 
Lead  sulphate    .    .    . 
Zinc  oxide  
Calcium  carbonate    . 
Silica  
Magnesium  silicate    . 
Undetermined,  color,  etc. 

100.0 

14.65 
0.34 
63.42 

20.91 
0.68 

100.0 

14.18 
0.27 
63.27 

20.14 
2.14 

100.0 

44.08 
4.62 
41.41 
4.59 

5.10 
0.20 

100.0 

27.29 
4.39 
50.94 
7.10 

6.94 
3.34 

100.0 

50.52 
0.00 
46.06 
3.18 

0.24 

100.0 

33.98 
2.84 
41.80 
6.94 
12.14 

2.30 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

Analyses  by  the  author. 


32  ANALYSIS  OF  MIXED  PAINTS. 

5.  Composition  of  colored  paints.    After  the  extraction 
of  the  vehicle  it  is  necessary  to  examine  the  pigment 
qualitatively  in  order  to  ascertain  the  ingredients  to  be 
determined.    The  usual  qualitative  scheme  may  be  fol- 
lowed with  advantage.    The  colors  as  given  on  the  color 
cards  of  paint  manufacturers  are  usually  confined  to  a 
limited  number  of  combinations,  the  possible  components 
of  which  may  be  easily  ascertained,  and  which,  in  fact, 
are  usually  well  known  to  paint    chemists;  but  to  the 
chemist  who  has  had  but  little  experience  along  paint 
lines,  the  following  tables  of  color  ingredients  will  be  of 
interest.     Unfortunately,    manufacturers  are   not  agreed 
among  themselves  as  to  standards  for  naming  colors;  for 
example,  a  tea  green  put  up  by  one  manufacturer  may  not 
correspond  with  a  tea  green  put  up  by  another;  but  by  a 
careful  study  of  the  color  cards  issued  by  reputable  paint 
manufacturers,  it  is  usually  possible  to  identify  the  color 
to  be  analyzed.    Also  the  same  or  closely  the  same  color 
may  be  produced  by  different  combinations  of  color  pig- 
ments, hence  it  is  necessary  to  state  all  of  the  possible 
constituents   that   may   be   used,  as   far   as  the  author 
has  been  able  to  ascertain  them,  even  though  it  is  quite 
probable  that  they  may  not  all  be  present  in  the  same 
paint. 

6.  Reds: 

Brick.     Base  white,  ochre  and  Venetian  red. 

Flesh  Color.  Base  white,  ochre,  Venetian  red,  and 
sometimes  orange  chrome  yellow. 

Indian  Red.    Indian  red. 

Lilac.  Ultramarine,  carmine,  Indian  red,  ochre,  lamp- 
black. 

Maroon.    Carmine,  ultramarine,  lampblack,  Tuscan  red. 

Pink.    Base  white,  orange  chrome  yellow. 


ANALYSIS  OF  MIXED  PAINTS.  33 

Terra  Cotla.    Base  white,  burnt  sienna,  umber,  chrome 

yellow,  Venetian  red,  ochre. 
Salmon.    Base  white,  vermilion,  lemon  chrome  yellow, 

sienna,  ochre,  Venetian  red,  orange  mineral. 
Tuscan  Red.    Tuscan  red,  Indian  red,  Para  vermilions. 
Venetian  Pink.     Base  white,  Venetian  red. 
Venetian  Red.     Venetian  red. 

7.  Blues: 

Azure  Blue.     Base     white,    ultramarine     blue,    chrome 

green,  Prussian  blue. 
Bronze  Blue.     Black,  Prussian  blue. 
Dark  Blue.    Base  white,  chrome  green,  Prussian  blue, 

ultramarine,  black. 

Light  Blue.    Base  white,  ultramarine,  Prussian  blue. 
Neutral  Blue.    Base  white,  Prussian  blue,  umber,  black. 
Robin's  Egg  Blue.    Base     white,    ultramarine,     lemon 

chrome  green. 
Sky  Blue.    Base    white,    cobalt    blue,    Prussian    blue, 

ultramarine  blue,  chrome  yellow. 

8.  Yellows: 

Buff.    Base  white,  ochre,  black,  red  chrome  lead. 
Canary.     Base    white,    lemon    chrome   yellow,    chrome 

green. 
Citron.     Base    white,    Venetian    red,    Prussian    blue, 

chrome  yellow. 

Cream.     Base  white,  ochre,  Venetian  red. 
Deep  Cream.    White,  ochre,  Venetian  red. 
Ecru.     Base  white,  ochre,  chrome  yellow,  black,  chrome " 

green. 

Ivory.     Base  white,  chrome  yellow,  ochre. 
Lemon.     Base  white,  chrome  yellow. 
Manilla.     Base  white,  ochre,  chrome  yellow. 


34  ANALYSIS  OF   MIXED   PAINTS. 

Stone.     Base  white,  ochre,  umber,  chrome  yellow. 
Straw.     Base  white,  chrome  yellow,  ochre,  Venetian  red. 

9.  Greens: 

Ivy  Green.     Ochre,  lampblack,  Prussian  blue. 

Light  Green.    White,  Prussian  blue,  chrome  green. 

Manse  Green.     Chrome  green,  chrome  yellow,  ochre. 

Moss  Green.  Base  white,  ochre,  chrome  green,  lamp- 
black. 

Olive  Green.  Lemon  chrome  yellow,  ochre,  ultramarine 
blue,  Prussian  blue,  Indian  red,  chrome  green,  lamp- 
black. 

Pea  Green.  Base  white,  chrome  green,  very  rarely 
emerald  green. 

Sap  Green.  '  Base  white,  chrome  yellow,  lampblack, 
chrome  green. 

Sea  Green.     Base  white,  chrome  green,  sienna,  ochre. 

Tea  Green.  Base  white,  chrome  green,  chrome  yellow, 
lampblack.  hi/^" 

Willow  Green.  Base  white-chrome  green,  umber,  ivory, 
black. 

10.  Browns: 

Acorn  Brown.    Sienna,  carmine,  Indian  red,  lampblack, 
ochre. 

Brown.     Indian  red,  lampblack,  ochre. 

Chocolate.    Similar  to  acorn  brown. 

Cork  Color.  Base  white,  ochre,  Indian  red,  lamp- 
black, umber. 

Dark  Drab.  Base  white,  Indian  red,  lampblack,  Prus- 
sian blue,  yellow  ochre. 

Doe  Color.  Base  white,  sienna,  umber,  ochre,  lamp- 
black. 

Dove  Color.  Base  white,  Prussian  blue,  lampblack, 
ochre,  Indian  red,  umber,  sienna. 


ANALYSIS  OF  MIXED  PAINTS.  35 

Drab.     Base  white,  umber,  Venetian  red,  yellow  ochre, 

black. 
Fawn.     Base    white,    ochre,     Indian    red,    lampblack, 

sienna,  umber,  chrome  yellow,  Venetian  red. 
Lava.     Base    white,     black,    chrome    orange,    chrome 

yellow. 

Sandstone.     Umber. 
Snuff  Brown.     Base  white,  ochre,  Indian  red,  Venetian 

red. 

1 1 .   Greys  and  grays : l 

Ash  Gray.  Base  white,  ochre,  lampblack,  sienna, 
ultramarine  blue. 

Dark  Slate.     Base  white,  Prussian  blue,  lampblack. 

French  Gray.  Base  white,  black,  ultramarine,  Prus- 
sian blue,  Venetian  red. 

Granite.     Base  white,  ochre,  lampblack. 

Gray  stone.  Base  white,  black,  Prussian  blue,  ultra- 
marine, Venetian  red. 

Lead.     Base  white,  lampblack,  Prussian  blue. 

Light  Grey.     Base  white,  lampblack,  Prussian  blue. 

Pearl.    Similar  to  French  gray. 

Silver  Gray.  Base  white,  ochre,  lampblack,  chrome 
yellow. 

Smoke  Gray.     Base  white,  ochre,  lampblack. 

Steel  Gray.     Base  white,  chrome  yellow,  lampblack. 

Stone  Gray.     Base  white,  chrome  yellow,  black. 

Warm  Gray.  Base  white,  ochre,  lampblack,  sienna, 
Prussian  blue. 

1  Grey  is  understood  to  mean  an  admixture  of  black  and  white, 
while  gray  is  an  admixture  of  black  and  white  to  which  another  color 
has  been  added,  provided,  of  course,  that  the  black  and  white  pre- 
dominate. 


CHAPTER  II. 

ANALYSIS  OF  THE  VEHICLE. 

12.  Water,     Occurrence.    A  fraction  of  1   per  cent  of 
water  may  occur  normally  in  the  vehicle.    A  small  per- 
centage, 1  to  3  per  cent,  may  be  incorporated  into  the 
paint  by  the  manufacturer  under  the  belief  that  it  secures 
better    penetration    when   applied    to    surfaces   that   are 
slightly  damp,  and  also  that  it  will  prevent  the  pigment 
from  settling  hard  in  the  can.      Oftentimes,  however,  large 
quantities  are  introduced  for  the  purpose  of  cheapening 
the  product.    The  water  may  be  added  to  the  paint  and 
prevented  from  separating  out,  by  forming  an  emulsion 
with  the  oil  with  the  aid  of  an  alkali,  or  by  grinding  it  into 
the  pigment,  using  an  adhesive  such  as  glue  or  casein.     In 
the  first  case  the  nature  of  the  ash  left  on  burning  some 
of  the  vehicle,  separated  as  described  under  Linseed  Oil, 
will  indicate  whether  an  alkali  has  been  used  or  not.     In 
the  second  case  the  vehicle  will  yield  less  than  one  per 
cent  of  water  when  distilled  with  a  dry,  inert  substance 
such  as  sublimed  lead,  as  the  water  remains  with  the 
pigment. 

13.  Detection.    Water  may  be  tested  for  qualitatively 
in  light  colored  paints,  by  rubbing  with  a  little  eosin  on  a 
glass  plate.    If  water  is  present  the  paint  will  take  on  a 
strong  pink  color,  otherwise  the  color  will  remain  prac- 
tically  unchanged.     If   the    paint    contains    considerable 
coloring  material,  rendering  the  eosin  test  inapplicable, 
a  weighed  strip  of  gelatine  may  be  immersed  in  the  paint 
for  several  hours.     If  water  is  present  the  gelatine  will 


ANALYSIS   OF  THE   VEHICLE.  37 

soften  and  increase  in  weight,  the  adhering  paint  being 
removed  by  the  use  of  petroleum  ether  and  drying  for  a 
minute  or  two  between  sheets  of  filter  paper.  An  immer- 
sion of  the  gelatine  for  18  to  24  hours  will  show  the  pres- 
ence of  water  in  a  paint  containing  as  little  as  2  per 
cent. 

14.  Estimation.  Quantitatively,  the  water  is  best  esti- 
mated by  distillation,  using  a  retort,  the  neck  of  which 
forms  the  inner  tube  of  a  condenser,  the  outside  tube  being 
a  Welsbach  chimney.  One  hundred  grams  of  the  paint 
is  weighed  into  an  aluminum  beaker  and  mixed  with  a 
thoroughly  dried,  inert  pigment  like  silica  or  sublimed 
lead  until  it  ceases  to  be  pasty,  and  then  transferred  to  the 
retort,  which  is  heated  in  an  oil  bath,  the  water  being 
collected  in  a  graduate  calibrated  to  fifths  of  cubic  centi- 
metres. Toward  the  end  of  the  distillation,  the  tempera- 
ture of  the  contents  of  the  retort  being  raised  to  200°  C., 
a  very  slow  current  of  air  or  illuminating  gas  is  admitted 
to  the  retort  through  a  tube  passing  nearly  to  the  surface 
of  the  pigment.  This  will  carry  over  the  last  traces  of 
moisture.  It  is  advisable  to  pass  the  illuminating  gas 
through  a  wash-bottle  containing  sulphuric  acid,  which 
not  only  serves  to  remove  moisture,  but  acts  as  an  indi- 
cator for  the  rate  of  flowing  gas.  The  heating  should  be 
continued  for  at  least  two  hours  at  the  above  temperature 
to  insure  the  complete  removal  of  the  combined  water 
from  the  basic  carbonate  of  lead  which  may  be  present. 
This  should  be  deducted  from  the  total  amount  of  water 
obtained,  by  multiplying  the  basic  carbonate  present  by 
2.3  per  cent,  which  represents  the  average  per  cent  of 
combined  water  in  white  lead.  It  is  impossible  to  re- 
move the  water  by  this  method,  without  decomposing 
part  of  the  lead  hydroxide  of  the  white  lead,  as  it  begins 
to  lose  the  combined  water  at  105°-120°  C.,  the  total 


38  ANALYSIS   OF  MIXED    PAINTS. 

combined  water  being  driven  off  at  150°  C.  for  6  hours 
with  little  or  no  loss  of  carbon  dioxide.  An  exposure  of 
4  hours  at  a  temperature  175°  results  in  the  loss  of  all 


FIG.  3.  — ESTIMATION  or  WATER. 

the  water  and  a  slight  amount  of  carbon  dioxide;  at  200° 
an  exposure  of  2  hours  is  sufficient  to  remove  all  of  the 
combined  water  and  about  one-quarter  to  one-third  of 
the  carbon  dioxide. 


ANALYSIS   OF  THE   VEHICLE.  39 

In  each  case  a  blank  should  be  run  in  order  to  ascertain 
that  the  inert  pigment  and  illuminating  gas  are  free  from 
condensible  moisture. 

The  author  believes  that  a  current  of  air  obtained  by 
the  use  of  an  aspirator  is  preferable  to  the  use  of  illumi- 
nating gas,  as  with  the  latter  there  is  the  possibility  of 
the  formation  of  water  from  the  hydrogen  of  the  illumi- 
nating gas  and  the  lead  oxide  present,  if  the  temperature 
is  raised  too  high. 

Of  eighty  mixed  paints  analyzed  by  the  author,  white 
and  gray  shades,  the  water  content  calculated  on  the 
basis  of  total  vehicle,  was  as  follows: 


Amount  of  Water.  Number  of 

Paints. 

0  to  1  per  cent 26 

1  to  3  per  cent 25 

3  to  6  per  cent 5 

6  to  10  per  cent 3 

10  to  24  per  cent 21 


15.  Linseed  oil.     Extraction  from  paint.    One  to  two 
hundred  grams  of  the  paint  are  heated  to  about  65°  C. 
on  the  water  bath  and  centrifuged  rapidly  until   the   oil 
is    freed  from    pigment.      This   operation    may   be  con- 
ducted with  advantage  in  a  steam-heated   Babcock  milk 
tester. 

1 6.  Estimation   of  the   volatile   oils.    The   clear  oil   is 
weighed  and  introduced  into  a  suitable  sized  Erlenmeyer 
flask  connected  with  a  rather  large  condenser.    The  con- 
tents of  the  flask  are  brought  to  130°  C.  by  means  of  an 
oil  bath  and  a  current  of  steam  conducted  through  the 
oil.    The  volatile  oils  rapidly  distil  over  and  are  collected 
in  a  weighed  short-stemmed  separatory  funnel,  the  water 
being  drawn  off  from  time  to  time  as  may  be  necessary. 


40  ANALYSIS   OF   MIXED   PAINTS. 

The  distillate  is  allowed  to  stand  for  several  hours  to 
insure  the  complete  separation  of  the  water,  which  is  then 
drawn  off  and  the  volatile  oils  weighed  and  bottled  for 
subsequent  examination.  The  aqueous  portion  of  the 
distillate  will  inevitably  carry  with  it  a  small  quantity  of 
volatile  oil,  but  the  amount  will  be  slight,  amounting  to 
about  0.4  gram  per  100  c.c.  of  water  distillate.  After 
calculating  the  percentage  of  volatile  oil,  the  linseed  oil  is 
calculated  by  difference,  by  subtracting  the  percentages 
of  volatile  oil  and  water  from  100. 

The  results  obtained  above  may  be  checked  up  by  weigh- 
ing 6  or  7  grams  of  the  thoroughly  stirred  paint  into  a 
weighed  petri-dish  and  heating  to  120°  C.  for  3  hours, 
cooling  in  a  desiccator  and  weighing.  A  pure  raw  or  boiled 
oil  will  undergo  no  appreciable  change  in  weight,  while  the 
volatile  matters  will  be  practically  all  driven  off.  Know- 
ing the  amount  of  vehicle  present,  the  percentage  of  the 
volatile  oils  may  be  readily  calculated,  and  likewise  the 
percentage  of  linseed  oil. 

The  linseed  oil,  after  being  freed  from  the  volatile  oils, 
is  allowed  to  stand  for  several  hours  in  a  warm  place  until 
thoroughly  settled,  and  may  then  be  tested  for  the  presence 
of  other  oils  as  follows. 

17.  Specific  gravity.  Determine  the  specific  gravity  by 
means  of  a  pycnometer  or  a  Westphal  balance. 

The  specific  gravity  may  fee  taken  at  room  temperature 
and  calculated  to  15.5°  C. 

Correction  for  1°  C.  =  .000650 
Correction  for  1°  F.  =  .000361 

The  usual  limits  for  pure  raw  oil  at  15.5°  C.  are  0.931 
to  0.937;  boiled  oils  usually  do  not  exceed  0.940.  A  low 
specific  gravity  may  indicate: 


I 

ANALYSIS   OF  THE   VEHICLE.  41 

a.  Mineral  oils. 

b.  Cotton-seed  oil. 

c.  Corn  oil. 

A  high  specific  gravity  may  indicate 

a.  Rosin  or  resinous  products. 

b.  Rosin  oils. 

c.  Excessive  heating   or  unusual  addition  of   metallic 
driers. 

18.  Spot  test.    One  or  2  c.c.  of  the  oil  are  poured  on  a 
porcelain  plate  and  a  drop  of  concentrated  sulphuric  acid 
added  carefully.     If  pure,  the  spot  formed  will  bear  a 
marked  resemblance  to  a  begonia  leaf.     If  rosin  or  rosin 
oil  be  present  a  black,  gummy  mass  immediately  results; 
cotton-seed  oil  gives  a  spot  without  the  characteristic  mark- 
ings of  the  linseed-oil  spot.     Mineral  oils  give  a  scum-band 
rapidly  spreading  out  over  the  surface  from  the  drop,  the 
margin  of  the  band  being  uniformly  circular.     Fish  oils 
give  a  similar  reaction,  but  the  margin  of  the  band  is  not 
at  all  uniform,  and  may  be   readily  distinguished    from 
mineral   oils.    With    a   little   practice  and  working  with 
oils  of  known  composition,  this  test  can  be  relied  upon 
to  detect  any  appreciable  adulteration  with   the    above 
oils. 

19.  Mineral  oils.    The  spot  test  for  petroleum  products 
may  be  confirmed  by  allowing  a  sample  of  the  oil  to  flow 
down  a  sheet  of  glass,  the  other  side  of  which  has  been 
painted    jet    black.     If    petroleum   products    are  present 
even  in  a  minute  quantity,  the  sample  will  exhibit  the 
"  bloom "    characteristic    of    mineral    oils.    A    standard 
sample   should    always    be    run    for    comparison.     It    is 
possible  to  remove  the  "  bloom  "  of  mineral  oils  by  the 


42  ANALYSIS   OF   MIXED   PAINTS. 

use  of  nitrobenzine  or  similar  compounds,  but  the  author 
is  of  the  belief  that  this  is  very  seldom  resorted  to  in  the 
paint  industry. 

Quantitatively  the  mineral  oil  may  be  estimated  by 
saponifying  10  grams  of  the  oil  with  alcoholic  potash 
for  2  hours,  using  a  return  condenser.  The  alcohol 
is  distilled  off  and  the  soap  dissolved  in  75  to  100  c.c. 
of  water,  transferred  to  a  separatory  funnel  and  50 
c.c.  of  ether  added.  The  liquids  are  then  shaken,  avoid- 
ing the  formation  of  an  emulsion  as  far  as  possible.  The 
aqueous  solution  is  then  drawn  off,  the  ethereal  layer 
washed  wtih  a  few  cubic  centimetres  of  water  to  which 
a  little  caustic  potash  has  been  added,  and  poured  into  a 
weighed  flask.  The  soap  solution  is  then  returned  to 
the  separator,  and  twice  extracted  with  ether  in  the 
same  way  as  before.  The  combined  ethereal  solutions 
are  distilled  off  on  the  water  bath,  the  flask  dried  and 
weighed.  The  increase  in  weight  represents  the  amount 
of  unsaponifiable  matter,  and  unless  rosin  oil  is  present, 
represents  the  mineral  oil  with  the  exception  of  about 
2  per  cent,  the  average  amount  of  unsaponifiable  matter 
in  linseed  oil. 

20.  The  mineral  oil  may  be  separated  from  the  rosin 
oil  in  the  unsaponifiable  material  by  heating  50  c.c.  of 
nitric  acid  of  1.2  specific  gravity  to  boiling  in  a  flask  of 
700  c.c.  capacity,  the  source  of  heat  removed,  and  the 
unsaponifiable  material  added.  The  flask  is  then  heated 
on  the  water  bath  with  frequent  shaking  for  about  one-half 
hour,  and  400  c.c.  cold  water  added.  After  cooling,  50  c.c. 
of  petroleum  ether  is  added  and  the  flask  agitated,  the 
mineral  oil  is  dissolved,  while  the  resinous  matters  remain 
in  suspension.  The  liquid  is  then  poured  into  a  separatory 
funnel,  leaving  behind  as  much  of  the  resinous  material  as 
possible.  After  settling,  the  aqueous  liquid  is  drawn  off 


ANALYSIS    OF    THE    VEHICLE.  43 

and  the  ethereal  layer  poured  into  a  weighed  flask. 
Another  portion  of  petroleum  ether  is  added  to  the  rosin 
remaining  in  the  flask,  and  allowed  to  act  upon  it  for  about 
ten  minutes,  when  it  is  added  to  that  in  the  weighed  flask. 
After  distilling  off  the  ether,  the  oil  is  weighed.  Mineral 
oils  lose  about  10  per  cent  when  treated  with  nitric  acid 
in  this  way,  and  hence  the  weight  of  the  oil  found  must  be 
divided  by  0.9  in  order  to  find  the  amount  present  in  the 
sample  analyzed. 

21.  Cotton-seed  oil.  This  oil  is  seldom  found  in  house 
paints,  but  is  often  used  in  certain  classes  of  barn  paints. 
The  spot  test  may  be  confirmed  by  the  Halphen  test,  the 
apparatus  required  being  a  large  test  tube  provided  with 
a  condensing  tube  and  a  brine  bath;  the  reagent  employed 
being  a  1.5  per  cent  solution  of  sulphur  dissolved  in  carbon 
bisulphide  with  an  equal  volume  of  amyl  alcohol  added. 
Equal  volumes  of  the  oil  and  reagent  are  heated  in  a  steam 
bath  at  first,  and  after  the  violent  boiling  has  ceased,  in  the 
brine  bath  at  105°-110°  C.  for  about  30  minutes.  As  little 
as  1  per  cent  of  cotton-seed  oil  will  give  a  crimson  wine 
coloration.  Cotton-seed  oil  heated  to  250°  C.  does  not 
respond  to  this  test. 

Quantitatively,  the  amount  of  cotton-seed  oil  can  only 
be  approximated  in  a  very  general  manner  by  means  of 
the  iodine  values. 

Let    x  —  percentage  of  one  oil,  and 
y  =  percentage  of  the  other  oil. 
m  =  average  iodine  value  of  pure  oil  x. 
n  =  average  iodine  value  of  pure  oil  y,  and 
/  =  iodine  value  of  sample  under  examination. 


Then    .  •        x 

m  —  n 


44  ANALYSIS    OF    MIXED    PAINTS. 

22.  Corn  oil.    This  oil  gives  a  spot  test  much  resem- 
bling that  given  by  linseed  oil,  but  may  be  detected  in  lin- 
seed oil,  if  in  quantity,  by  the  following  test.     Dilute  with 
four  volumes  of  benzine,  add  one  volume  of  strong  nitric 
acid,  shake.     Linseed  oil  turns  a  white  color,  while  corn 
oil  turns  to  a  reddish  orange. 

Quantitatively,  corn  oil  can  be  estimated  only  approxi- 
mately when  in  linseed  oil  by  the  same  method  used  for 
cotton-seed  oil. 

23.  Fish  oils.     In  addition  to  the  spot  test  these  oils 
may  be  detected  by  rubbing  a  little  of  the  sample  vigorously 
between  the  palms  of  the  hands.     Fish-oil  mixtures  give 
the  characteristic  odor  of  oils  of  this  class. 

In  mixtures  with  linseed  oil,  the  amount  present  can 
only  be  determined  crudely  by  means  of  the  "  rise  of  tem- 
perature "  with  sulphuric  acid  with  the  Maumene  appara- 
tus described  under  the  analysis  of  the  Volatile  Oils.  Allen 
found  the  rise  of  temperature  with  sulphuric  acid  to  be  104 
to  111  in  the  case  of  linseed  oil,  and  126  in  the  case  of 
menhaden  oil. 

24.  Rosin    and    rosin   oils.    These    products   are    best 
detected  qualitatively  by  means  of  the  Lieberman-Storch 
reaction,  which  is  of  sufficient  delicacy  to  detect  the  pres- 
ence of  even  very  small  quantities  of  rosin  oil  or  rosin 
drier  in  boiled  oil.     One  to  2  c.c.  of  the  oil  under  exami- 
nation are  shaken  in  a  test  tube  with  acetic  anhydride  at 
a  gentle  heat, 'cool,  pipette  off  the  anhydride  and  place  a 
few  drops  on  a  porcelain  crucible-cover  and  add  one  drop 
of  sulphuric  acid    (34.7  c.c.  sulphuric  acid  and  35.7  c.c. 
water)  so  that  it  will  mix  slowly.     If  rosin  or  rosin  oil  is 
present,  a    characteristic,    violet,    fugitive     color   results. 
Certain  fish  oils  will  give  a  very  similar  color,  but  if  present 
are  easily  detected  by  the  fish-like  odor  of  the  oil  on 
warming. 


ANALYSIS    OF    THE    VEHICLE.  45 

Old  samples  of  pure  boiled  oil  give  a  color  that  might  be 
easily  mistaken  for  rosin  or  rosin  oils;  in  such  cases  it  is 
best  to  warm  the  oil  with  alcohol  so  as  to  extract  the  bulk 
of  rosin  present  and  test  the  alcoholic  extract.  Rosin  may 
be  more  completely  separated  and  estimated  by  Twitchell's 
process  (J.  Soc.  Chem.  Ind.,  1891, 10,  804)  or  by  Cladding's 
method  (Amer.  Chem.  J.,  3,  416).  This  process  depends 
upon  the  solubility  of  silver  resinate  in  ether,  while  the 
silver  salts  of  fatty  acids  are  insoluble. 

A  much  used  test  for  determining  the  presence  of  a 
cheap  rosin  drier  in  boiled  linseed  oil,  is  to  make  a  paste 
with  the  suspected  oil  and  moisture-free  litharge.  If  of 
good  quality,  the  paste  should  not  thicken  or  harden 
inside  of  24  to  48  hours.  If  such  hardening  occurs,  the 
oil  should  be  condemned.  A  standard  sample  of  oil 
should  be  run  for  comparison  each  time. 

25.  In  the  preparation  of  gloss  paints  a  little  varnish 
is  added,  the  gums  of  which  might  be  mistaken  in  the  above 
tests  for  rosin.     In  the  cheaper  paints  a  large  excess  of 
rosin  is  used  in  the  resinate  drier  added.    An  easy  method 
of  detecting  rosin  and  other  rosins  and  estimating  the  rela- 
tive amount  present,  is  to  stir  up  about  100  grams  of  the 
paint  with  500  c.c.    petroleum  ether,  allow    to  stand  24 
hours,  siphon  off  the  ether,  and  examine  the  skin  formed 
on  top  of  the  pigment.     This  will  harden  in  the  course  of 
another  day  so  that  it  may  be  removed,  placed  on  a  watch 
glass,  washed  free  of  adhering  pigment  with  more  petro- 
leum ether  and  dried.     The  color  and  other  physical  prop- 
erties will  enable  one  to  judge  whether  it  is  rosin  or  some 
of  the  other  varnish  gums. 

26.  Linseed  oil  from  inferior  seed.    This  includes  oil 
prepared  from  impure  or  adulterated  seed,  giving  an  oil  of 
inferior  quality;  or,  what  is  essentially  the  same  thing,  the 
screened  foreign  seeds  are  separately  crushed  and  pressed 


46  ANALYSIS   OF  MIXED   PAINTS. 

and  the  resulting  oil  used  to  blend  with  a  pure  linseed  oil. 
Such  oils  dry  slowly  and  imperfectly,  and  the  resulting 
film  lacks  the  "  hardness  "  given  by  the  pure  oils,  and  often 
give  the  consumer  as  just  cause  for  complaint  as  the  more 
grossly  adulterated  varieties. 

When  sold  as  raw  oil,  such  oils  usually  have  a  greenish 
tinge  which  disappears  or  is  masked  in  the  boiling.  Chemi- 
cally this  form  of  adulteration  is  more  difficult  to  detect 
than  when  other  oils  of  distinctively  different  chemical 
properties  are  used.  With  this  class  of  oils,  the  specific 
gravity,  iodine  number,  saponification  value,  and  unsaponi- 
fiable  matter  remain  nearly  normal,  and  the  leading  tests 
that  may  be  applied  to  such  suspected  oils  are  their  oxygen 
absorption  power  and  the  time  required  for  drying.  Both 
the  per  cent  of  oxygen  and  the  rate  of  absorption  will  be 
found  markedly  lower,  depending  on  the  amount  of  foreign 
seed  oil  present.  In  order  to  obtain  comparable  results, 
a  standard  oil  of  known  purity  should  be  carried  through 
the  tests  along  with  the  suspected  oil,  as  the  weather 
conditions  may  seriously  affect  the  rate  of  drying. 

27.  Spread  about  one  gram  of  precipitated  lead,  weighed 
off  accurately,  on  a  somewhat  large  watch  glass  in  a  thin 
layer,  and  then  allow  to  fall  on  to  it  from  a  pipette  0.6  to 
0.7  gram  (not  more)  of  the  oil  to  be  tested,  placing  each 
drop  on  a  different  portion  of  the  lead,  and  taking  care 
that  the  drops  do  not  run  into  one  another.  Then  allow 
the  watch  glass  to  stand  at  the  ordinary  temperature  in  a 
place  exposed  to  light  and  protected  from  falling  dust. 
Weigh  at  frequent  intervals  in  order  to  note  the  rapidity 
with  which  the  oil  is  absorbing  oxygen  and  to  determine 
accurately  when  the  oil  ceases  to  gain  in  weight.  The 
lead  powder  is  prepared  by  precipitating  a  lead  salt  with 
zinc,  washing  the  precipitate  rapidly  in  succession  with 
water,  alcohol  and  ether,  and  finally  drying  in  a  vacuum. 


ANALYSIS   OF  THE  VEHICLE.  47 

A  weighed  quantity  of  the  oil  will  gain  16  to  11  \  per  cent 
in  weight  in  drying;  boiled  oil  somewhat  less,  varying  from 
15  to  17  per  cent. 

Instead  of  precipitated  lead,  thin  aluminum  plates  3 
inches  by  6  inches  may  be  used.  The  plates  are  weighed, 
and  0.1  gram  to  0.2  gram  of  oil  rubbed  over  the  plate,  giving 
a  thin  uniform  film,  weighed,  set  aside  in  a  dust-free  place, 
and  the  increase  in  weight  noted  from  time  to  time. 

28.  Specifications  for  boiled  linseed  oil,  Navy  Depart- 
ment, 1905.  Must  be  absolutely  pure  kettle-boiled  oil  of 
the  best  quality,  and  the  film  left  after  flowing  the  oil  over 
glass  and  allowing  it  to  drain  in  a  vertical  position  must 
dry  free  from  tackiness  in  12  hours  at  a  temperature  of 
70°  F. 

It  must  contain  no  rosin.  The  specific  gravity  must  be 
between  0.934  and  0.940  at  60°  F. 

To  be  purchased  by  the  commercial  gallon;  to  be  in- 
spected by  weight,  and  the  number  of  gallons  to  be  deter- 
mined at  the  rate  of  7J  pounds  of  oil  to  the  gallon. 


CHAPTER  III. 

ANALYSIS  OF  THE  VOLATILE  OILS. 

29.  Identification.  The  volatile  oil  distilled  from  lin- 
seed oil  is  tested  qualitatively  for  spirits  of  turpentine, 
stump  turpentines,  rosin  spirit,  petroleum  naphtha  and 
benzole  by  the  following  test.1 

Shake  in  a  test  tube  equal  volumes  of  the  turpentine 
to  be  tested  and  concentrated  sulphurous  acid  until  quite 
thoroughly  mixed.  Set  aside,  noting  the  time  of  separation 
and  the  color  of  the  two  strata.  Samples  of  known  purity 
should  be  run  alongside  of  the  sample  to  be  tested,  and  the 
time  of  shaking  the  samples  should  be  as  uniform  as  pos- 
sible. Deadwood  turpentine  if  highly  rectified  gives  a 
reaction  approaching  that  of  livewood  turpentines. 

1.    American  Turpentine. 

Separation  takes  place  very  slowly. 
Upper  Stratum  —  Opaque ;  milky  white. 
Lower  Stratum  —  Translucent;  milky  white. 
Odor  —  Slight  terpene  smell. 

2.    Russian  Turpentine. 

Quick  separation. 

Upper  Stratum  —  Translucent;  faint  turbidity. 

Lower  Stratum  —  Clear  and  colorless. 

Odor  —  Slight  pungent  smell. 

1  Scott's  Test  for  Turoentines,  Drugs,  Oils  and  Paints,  1906. 

48 


ANALYSIS  OF  THE   VOLATILE  OILS.  49 

3.  Deadwood  Turpentine. 
Medium  slow  separation. 

Upper  Stratum  —  Opaque ;  light  buff  color. 
Lower  Stratum  —  Translucent;  yellow-amber  color. 
Odor  —  Distinct  tar  smell. 

4.  Livewood  Turpentine. 
Medium  quick  separation. 

Upper  Stratum  —  Translucent ;  lemon  yellow  color. 
Lower  Stratum  —  Clear  and  colorless. 
Odor  —  Mild  tar  smell. 

5.   Rosin  Spirit. 
Medium  slow  separation. 

Upper  Stratum  —  Translucent;  golden-yellow  color. 
Lower  Stratum  —  Translucent;  creamy-white  color. 
Odor  —  Pungent  rosin  smell. 

6.   Benzine  (Petroleum  Naphtha). 
Quick  separation. 

Upper  Stratum  —  Clear  and  colorless. 
Lower  Stratum  —  Clear  and  colorless. 
Odor  —  Sulphurous  smell. 

7.    Benzole. 
Quick  separation. 

Upper  Stratum  —  Slight  turbidity;  faint  yellow  color. 
Lower  Stratum  —  Clear  and  colorless. 
Odor  —  Benzole  and  sulphurous  smell. 

30.  Estimation  of  petroleum  products.  If  the  qualita- 
tive test  indicates  the  presence  of  live  or  dead  wood  tur- 
pentine in  appreciable  quantities,  the  amount  of  petroleum 
product  that  may  be  present  is  best  estimated  as  follows: 

A  measured  quantity  of  the  volatile  oil  is  allowed  to 
drop  slowly  into  300  c.c.  of  fuming  nitric  acid,  contained 


50  ANALYSIS  OF   MIXED   PAINTS. 

in  a  flask  provided  with  a  return  condenser  and  immersed 
in  cold  water.  A  violent  reaction  takes  place,  and  the 
flask  should  be  shaken  occasionally.  When  all  action  has 
ceased  the  contents  of  the  flask  is  poured  into  a  separatory 
funnel  and  thoroughly  washed  with  successive  portions  of 
hot  water  to  remove  the  products  of  the  action  of  the  acid 
on  the  turpentine.  The  remaining  petroleum  oil  is  sepa- 
rated and  measured  or  weighed. 

31.  Wood  turpentine  being  absent,  the  amount  of  petro- 
leum products  may   be    very    closely    approximated    by 
the  "  Sulphuric  Acid  Number." 

The  apparatus  and  materials  required  being  a  large  test 
tube  of  considerable  diameter,  bedded  in  closely  packed 
cotton,  in  a  fibre  mailing  case  of  suitable  size,  a  thermome- 
ter provided  with  a  platinum  flange  attached  to  the  lower 
end,  the  lower  part  of  the  flange  being  bent  at  right 
angles  to  the  stem  of  the  thermometer.  A  mailing  case 
packed  with  cotton  offers  considerable  advantages  over  the 
regulation  asbestos  fibre  mixed  with  plaster  of  Paris,  in 
that  if  the  test  tube  is  broken  during  the  estimation,  the 
bottom  of  the  mailing  case  may  be  readily  removed  and 
the  acid  soaked  cotton  replaced  at  once  with  fresh,  while 
the  plaster  of  Paris  composition  has  to  be  washed  and  dried 
out,  an  operation  requiring  several  hours. 

32.  A  neutral  mineral  oil  is  required  giving  a  rise  when 
treated  with  sulphuric  acid  of  not  more  than  3°C.    Also 
a  standard  bottle  of  concentrated  sulphuric  acid  kept  for 
this  purpose  and  a  sample  of  turpentine  known  to  be  pure. 
Fifty  c.c.  of  the  neutral  oil  are  pipetted  into  the  large  test 
tube,  the  temperature  noted,  and  20  c.c.  of  the  acid,  of  the 
same  temperature,  added  from  the  burette  in  a  steady 
stream,  stirring  rapidly  meanwhile  with  a  uniform  motion 
to  maximum  temperature,  which  is  noted.    After  cleaning 
and  cooling  the  apparatus,  the  experiment  is  repeated 


ANALYSIS   OF  THE   VOLATILE  OILS.  51 

exactly  as  before,  but  with  the  addition  of  10  c.c.  of  pure 
turpentine  to  the  neutral  oil.  The  rise  in  temperature  is 
again  noted.  Similar  determinations  are  made  with  mix- 
tures of  50  per  cent  of  turpentine  and  50  per  cent  benzine, 
and  also  of  75  per  cent  of  turpentine  and  25  per  cent  of 
benzine.  Having  thus  ascertained  standards  for  compari- 
son, 10  c.c.  of  the  sample  under  examination  is  carried 
through  in  exactly  the  same  manner,  the  maximum  tem- 
perature noted  and  the  per  cent  of  turpentine  and  of  petro- 
leum product  calculated.  Commercially  pure  turpentines 
will  give  closely  uniform  results;  wood  turpentines  give 
lower  figures  which  approach  that  of  turpentine  the  more 
carefully  the  product  is  prepared  and  purified.  Rosin 
spirits  give  a  rise  of  7°  to  10°  C.,  benzine  and  benzole  3° 
to  8°  C. 

Samples  of  turpentine  which  have  been  exposed  to 
strong  light  are  liable  to  have  undergone  oxidation  changes 
which  will  markedly  affect  the  "  temperature  rise."  In 
which  case,  Mcllhiney's  bromine  addition  and  substitution 
method  will  serve  to  distinguish  such  oxidized  turpentines. 

A  scheme  much  in  use  by  some  paint  chemists  for  sep- 
arating mixtures  of  turpentine  and  benzine  is  to  introduce 
15  c.c.  of  the  suspected  sample  into  a  glass-stoppered 
cylinder  graduated  to  tenths  of  cubic  centimetres,  and 
then  add  35  c.c.  of  cold  concentrated  sulphuric  acid.  Shake 
carefully  12  to  20  times,  keeping  the  top  of  the  cylinder 
turned  away  from  operator.  Allow  to  stand  over  night, 
and  read  off  the  volume  of  the  benzine  layer  direct,  the 
turpentine  portion  having  combined  with  the  sulphuric 
acid.  There  is  considerable  danger  of  an  explosion  in 
using  this  method;  the  danger,  however,  may  be  much 
reduced  by  cooling  both  the  sample  and  acid  to  below  10°  C. 


52 


ANALYSIS  OF  MIXED  PAINTS. 


33.   ANALYSES   OF   VOLATILE   OILS   BY  THE  AUTHOR. 


No. 

Name 
of  Oil. 

Sp.  Gr. 
at  22°C. 

Odor. 

Rise 
0  C. 

Separation 

Lower 
Layer. 

Upper  Layer. 

1 

Terraben- 
tine 

.808 

Petroleum 

6° 

Immediate 

Clear 

Slightly  Milky 

2 

Turpentine 

.855 

Camphor 

52.5° 

Rapid 

Almost 

Lemon 

Oil 

Clear 

3 

Turpentine 

.862 

Character- 

57.0° 

Medium 

Milky 

istic  Tur- 

JVlilkv 

4 

Off  Color 

pentine 

Turpentine 

.857 

30.5° 

Slow 

Clear 

Clear 

5 

Turpentine 

.853 

" 

48.3° 

Slow 

Milky 

Milky 

6 

Turpentine 

.860 

it 

56.7° 

Medium 

Milky 

Slight  tinge 
of  Yellow 

7 

Wood  Spir- 

Stump 

its  Turpen- 

Turpentine 

52.8° 

Slow 

Deep 

Milky 

tine 

.859 

Lemon 

8 

Turpalin 

Petroleum 

1.0° 

Quick 

Clear 

Clear 

Base 

.862 

No.  1.     Petroleum  product,  probably  of  Russian  origin. 

No.  2.     Wood  turpentine. 

No.  3.     Commercially  pure  turpentine. 

No.  4.  Spirits  of  turpentine  containing  about  50  per  cent  petro- 
leum naphtha. 

No.  5.  Spirits  of  turpentine  containing  about  15  per  cent  petro- 
leum naphtha. 

No.  6.     Poorly  rectified  turpentine. 

No.  7.     Stump  turpentine. 

No.  8.     Petroleum  product. 

34.  Excessive  use  of  volatile  oils.  An  excess  of  thinners 
or  volatile  oils  is  detrimental  to  the  life  of  the  paint.  Sabin, 
in  his  work  on  "  The  Technology  of  Paint  arid  Varnish," 
writes  as  follows: 

"  Most  of  the  failures  of  lead  and  zinc  paints  are  due  to 
the  use  of  these  volatile  thinners  (turpentine  and  benzine). 
If  raw  linseed  oil  is  used,  it  may  be  desirable  to  add  5  per 
cent  of  a  good  drier.  This  should  be  pale  in  color,  indi- 
cating that  it  has  been  made  at  a  low  temperature,  and 
should  be  free  from  rosin.  The  latter  is  not  an  easy  thing 
to  detect,  but  if  a  fair  price  is  paid,  say  $1.50  to  $2.00  a 
gallon  at  retail,  and  freedom  from  rosin  is  guaranteed  by 
a  maker  of  good  reputation,  the  buyer  ought  to  feel 
safe." 


ANALYSIS  OF  THE  VOLATILE  OILS.  53 

The  presence  of  a  large  amount  of  thinners  renders  the 
paint  easier  to  brush  out,  and  hence  the  tendency  has  been 
to  increase  the  amount  of  thinners,  especially  benzine 
because  of  its  low  cost,  in  mixed  paints,  resulting  in  the 
reducing  of  the  linseed  oil  to  a  percentage  below  that 
required  to  give  the  proper  life  to  the  paint.  The  better 
class  of  paint  manufacturers  seem  to  consider  4  to  9  per 
cent  of  thinners  sufficient  for  outside  house  paints. 

Of  71  analyses  of  white  and  gray  mixed  paints  made 
by  the  author,  the  amount  of  thinners  came  between  the 
following  limits: 


Per 
Thii 
Ot 
4 
5 
6 
7 
8 
9 
10 
11 
12 

cent 
iners. 
o    4      

Number  of 
Paints. 
6 

5      

5 

6      

1 

7      

6 

8      

10 

9      

5 

10      

.    .                                    11 

11      

.    .                                            4 

12      

2 

29 

21 

Excluding  the  21  paints  containing  12  per  cent  of  thin- 
ners and  over,  the  average  amount  of  thinners  in  the 
remaining  50  paints  was  7.3  per  cent.  The  paints  high  in 
thinners  were,  in  almost  every  case,  inferior  paints,  high 
in  inert,  pigments. 


CHAPTER  IV. 

SPECIAL  METHODS  ON  OIL  ANALYSIS. 

35.  Determination  of  the  Iodine  Number.    The  newer 
Hanus  method  for  the  estimation  of  the  iodine  number  is 
to  be  preferred  to  the  older  standard  Hubl  method,  as  the 
Hubl  solution  rapidly  loses  strength  on  standing,  is  very 
slow  in  its  reaction,  and    nearly  every  chemist  using  it 
employs  a  modification  of  his  own,  especially  as  regards 
the  time  for  the  solution  to  remain  in  contact  with  the  fat 
or  oil,  and  hence  very  different  results  may  be  obtained 
on  the  same  oil  or  fat  by  different  investigators.    Com- 
parative tests  by  the  two  methods  made  in  this  laboratory 
gave  results  which  varied  only  a  few  tenths  of  one  unit  with 
oils  of  medium  iodine  values. 

36.  Preparation    of    Reagents.     Iodine    Solution.     Dis- 
solve  13.2  grams  of  iodine  in  1000  c.c.  glacial  acetic  acid 
(99.5  per  cent  acid,  showing  no  reduction  with  bichromate 
and  sulphuric  acid);  add  enough  bromine  to  double  the 
halogen  content  determined  by  titration  —  3  c.c.  of  brom- 
ine is  about  the  proper  amount.    The  iodine  may  be  dis- 
solved by  the  aid  of  heat,  but  the  solution  should  be  cold 
when  bromine  is  added. 

Dednormal  sodium  thiosulphate  solution.  Dissolve  24.8 
grams  of  chemically  pure  sodium  thiosulphate,  freshly 
pulverized  as  finely  as  possible  and  dried  between  filter  or 
blotting  paper,  and  dilute  with  water  to  one  litre  at  the 
temperature  at  which  the  titrations  are  to  be  made. 

Starch  paste.  One  gram  of  starch  is  boiled  in  200  c.c. 
of  distilled  water  for  ten  minutes  and  cooled  to  room  tem- 
perature. 

64 


SPECIAL  METHODS  ON  OIL  ANALYSIS.  55 

Solution  of  potassium  iodide.  One  hundred  and  fifty 
grams  of  potassium  iodide  are  dissolved  in  water  and  made 
up  to  one  litre. 

Dednormal  potassium  bichromate.  Dissolve  4.9066 
grams  of  chemically  pure  potassium  bichromate  in  distilled 
water,  and  make  the  volume  up  to  one  litre  at  the  tempera- 
ture at  which  the  titrations  are  to  be  made.  The  bichro- 
mate solution  should  be  checked  against  pure  iron. 

37.  Determination.  Standardizing  the  sodium  thiosul- 
phate  solution.  Place  20  c.c.  of  the  potassium  bichromate 
solution,  to  which  has  been  added  10  c.c.  of  the  solution  of 
potassium  iodide,  in  a  glass-stoppered  flask.  Add  to  this 
5  c.c.  of  strong  hydrochloric  acid.  Allow  the  solution  of 
sodium  thiosulphate  to  flow  slowly  into  the  flask  until  the 
yellow  color  has  almost  disappeared.  Add  a  few  drops  to 
the  starch  paste,  and  with  constant  shaking  continue  to 
add  the  sodium  thiosulphate  until  the  blue  color  just 
disappears. 

Weighing  the  sample.  Weigh  about  0.5  gram  of  fat  or 
0.250  gram  of  oil  on  a  small  watch  glass  or  by  other  suitable 
means.  With  drying  oils  which  have  a  very  high  absorbent 
power  0.100  to  0.200  gram  should  be  taken.  The  fat  is 
first  melted,  mixed  thoroughly,  poured  on  to  the  crystal  and 
allowed  to  cool.  Introduce  the  watch  crystal  into  a  wide 
mouth  16-oz.  bottle  with  a  ground-glass  stopper. 

Absorption  of  iodine.  The  fat  or  oil  in  the  bottle  is  dis- 
solved in  10  c.c.  chloroform.  After  complete  solution  has 
taken  place,  25  c.c.  of  the  iodine  solution  are  added. 
Allow  to  stand  with  occasional  shaking  for  45  minutes. 
The  excess  of  iodine  should  be  at  least  60  per  cent  of  the 
amount  added. 

Titration  of  the  unabsorbed  iodine.  Add  10  c.c.  of  the 
potassium  iodide  solution  and  shake  thoroughly,  then  add 
100  c.c.  of  distilled  water  to  the  contents  of  the  bottle. 


56  ANALYSIS   OF  MIXED   PAINTS. 

Titrate  the  excess  of  iodine  with  the  sodium  thiosulphate 
solution,  which  is  added  gradually,  with  constant  shaking, 
until  the  yellow  color  of  the  solution  has  almost  disap- 
peared. Add  a  few  drops  of  starch  paste  and  continue 
the  titration  until  the  blue  color  has  entirely  disappeared. 
Toward  the  end  of  the  reaction  stopper  the  bottle  and 
shake  violently,  so  that  any  iodine  remaining  in  solution 
in  the  chloroform  may  be  taken  up  by  the  potassium 
iodide  solution. 

Setting  the  value  of  the  iodine  solution.  —  At  the  time  of 
adding  the  iodine  solution  to  the  fat,  two  bottles  of  the 
same  size  as  those  used  for  the  determination  should  be 
employed  for  conducting  the  operation  described  above, 
but  without  the  presence  of  any  fat.  In  every  other 
respect  the  performance  of  the  blank  experiments  should 
.be  just  as  described.  These  blank  experiments  should  be 
made  each  time  the  iodine  solution  is  used.  Great  care 
must  be  taken  that  the  temperature  of  the  solution  does 
not  change  during  the  time  of  the  operation,  as  acetic  acid 
has  a  very  high  coefficient  of  expansion,  and  a  slight  change 
of  temperature  makes  an  appreciable  difference  in  the 
strength  of  the  solution. 

38.    IODINE  NUMBERS  OF  VARIOUS   OILS. 

Raw  linseed  oil 170-188 

Boiled  linseed  oil 164-188 

Bleached  linseed  oil 160 

Chinese  wood  oil 163 

Com  oil 111-123 

Cotton-seed  oil 101-117 

Fish  oil 148-160 

Turpentine 331-368 

39.   Determination   of   the   bromine    absorption   of   oils, 
Mcllheney's  method.1     The  advantage  of  this  method  is, 
»  J.  Am.  Chem.  Soc.  XXI,  1084. 


SPECIAL  METHODS  ON   OIL  ANALYSIS.  57 

that  the  absorption  of  halogen  by  addition  is  determined 
separately  from  the  absorption  by  substitution,  resulting 
in  additional  information  as  to  the  nature  of  the  substance. 
The  process  as  at  present  used  is  as  follows:  A  quantity 
of  the  oil  to  be  analyzed  is  weighed  into  a  glass-stoppered 
bottle,  10  c.c.  of  carbon  tetrachloride  added  to  dissolve 
the  oil,  and  20  c.c.  of  third-normal  bromine  in  carbon 
tetrachloride  added  from  a  pipette.  It  is  not  found  neces- 
sary in  filling  the  pipette  with  bromine  solution  to  use 
any  special  arrangement  to  prevent  the  introduction  of 
bromine  vapor  into  the  mouth.  Only  a  rubber  tube  is 
necessary.  Another  pipette  full  of  solution  should  be 
added  to  10  c.c.  of  carbon  tetrachloride,  and  this  blank 
titrated  with  thiosulphate  to  determine  the  strength  of  the 
bromine  solution.  The  test  itself  need  be  allowed  to  stand 
only  one  or  two  minutes  before  adding  20  to  30  c.c.  of  10 
per  cent  solution  of  potassium  iodide,  the  amount  neces- 
sary depending  upon  the  excess  of  bromine  present.  An 
excess,  of  course,  does  no  harm.  In  order  to  prevent  any 
loss  of  bromine  or  hydrobromic  acid  which  would  probably 
occur  on  removing  the  stopper  of  the  bottle,  a  short  piece 
of  wide  rubber  tubing,  of  the  sort  used  for  Gooch  crucibles, 
is  slipped  over  the  lip  of  the  bottle  so  as  to  form  a  well 
around  the  stopper.  It  is  advisable,  also,  to  cool  the 
bottle  by  setting  it  into  cracked  ice  in  order  to  produce  a 
partial  vacuum  in  the  interior.  Into  the  well  formed  by 
the  rubber  tubing  is  poured  the  solution  of  potassium 
iodide  and  the  stopper  opened  slightly.  If  the  bottle  has 
been  cooled  with  ice  the  iodide  solution  will  be  sucked 
into  the  bottle,  and  if  it  was  not  cooled  some  of  the  air 
from  the  interior  of  the  bottle  will  bubble  through  the 
iodide  solution,  being  thereby  washed,  and  allow  the  iodide 
solution  to  enter  the  bottle.  When  sufficient  iodide  solu- 
tion has  been  introduced  the  bottle  is  agitated  to  insure 


58  ANALYSIS   OF   MIXED   PAINTS. 

the  absorption  of  the  bromine  and  hydrobromic  acid  by 
the  aqueous  solution.  The  iodine  now  present  is  titrated 
with  tenth-normal  sodium  thiosulphate,  and  when  the 
titration  is  finished  5  c.c.  of  a  neutral  2  per  cent  solution 
of  potassium  iodate  are  added.  This  liberates  a  quantity 
of  iodine  equivalent  to  the  hydrobromic  acid  formed,  and 
on  titrating  this  iodine  the  bromine  substitution  figure 
may  be  calculated.  The  solution  of  potassium  iodate 
should  be  tested  for  acidity  by  adding  a  measured  quantity 
to  a  solution  of  potassium  iodide,  and  if  any  iodine  is  lib- 
erated it  should  be  determined  with  thiosulphate  and  a 
suitable  correction  introduced  into  the  calculation.  The 
potassium  iodide,  the  thiosulphate  solution,  and  the  water 
used  should  all  be  tested  to  see  that  they  are  neutral. 

The  reaction  between  bromine  and  oil  appears  to  be 
practically  instantaneous  as  far  as  the  bromine  taken  up 
by  addition  is  concerned,  but  it  seems  likely  that  substi- 
tution is  distinctly  affected  by  the  length  of  time  that  the 
oil  and  bromine  are  allowed  to  remain  in  contact. 


SPECIAL  METHODS   ON   OIL  ANALYSIS. 
40.   Bromine  values  of  various  oils. 


59 


/ 

1 

p 

P«B 

Bromine  calculated 
from  Hubl. 

Per  cent  of  bromine 
absorbed. 

Bromine  addition 
figure. 

Bromine  substitution 
figure. 

Bromine  from  Hubl  di- 
vided by  bromine  addi- 
tion figures. 

Raw  linseed  oil,  several 
years  old    
Raw  linseed  oil,  several 
years  old        .... 

1 

9 

166.9 
157.3 

105.2 
99.1 

98.4 
99.2 

95.4 
92.0 

1.5 

3.6 

1.103 
1.000 

Raw  linseed  oil     ... 
Do      

3 
4 

184.2 
178.6 

116.1 
112.6 

116.1 
108.5 

109.6 
102.1 

3.4 
3.2 

1.059 
1.102 

Do      

5 

185.9 

117.2 

113.2 

109.2 

2.0 

1.072 

Do  

6 

186.3 

117.0 

112.2 

106.5 

2.9 

1.098 

Do 

7 

104  5 

99  9 

2.3 

Do 

s 

115  1 

109  5 

2.8 

Do 

q 

114  6 

109  4 

2.6 

Average  omitting  Nos. 
1  and  2  
• 

Boiled  linseed  oil      .    . 
Do 

1 
2 

183.8 

180.4 
183  3 

115.7 

113.7 
115  5 

112.0 

106.0 
110  8 

106.6 

100.8 
105  8 

2.7 

2.6 
2  5 

1.083 

1.126 
1  091 

Do 

3 

105  4 

101  2 

2  1 

Do 

4 

110  0 

103  2 

3.4 

Do  
Do  
Do          ... 

5 
6 

7 

109.8 
113.6 
109  2 

105.2 
103.0 
103  8 

2.3 
5.3 
2.7 

Do  

8 

110.8 

101.0 

4.9 

Averages    

109.5 

103.0 

3.2 

Third  run  rosin  oil  .    . 
Do 

1 

9 

63  9 

40  3 

197.6 
92  3 

16.4 

7  7 

90.6 
42  3 

5  231 

"Mystic"   brand  rosin 
oil 

93  7 

6  3 

43  7 

"Java"  boiled  rosin  oil 
Corn  oil      

1 

73.3 

46.2 

101.9 
76.2 

8.3 
73.8 

46.8 
1.2 

5.685 

Do  

?, 

75.8 

73.2 

1.3 

Do  

3 

75.4 

71.6 

1.9 

Averages   

75.8 

72.9 

1.5 

60  ANALYSIS   OF  MIXED   PAINTS. 

41.  Estimation    of    rosin    in    mixtures    of    linseed    oil 
and  mineral  oil.    Twitchell's  method.    A  weighed  portion 
of  the  sample  is  saponified  by  boiling  with  alcoholic  potash; 
the  alcohol  is  driven  off  by  prolonged  boiling  after  diluting 
with  water.    The    unsaponifiable    matter    is    shaken  out 
with  petroleum  ether  as  previously  described  under  Lin- 
seed Oil.    The  remaining  soap  solution  made  acid  yielding 
a  mixture  of  fatty  and  rosin  acids.     Heat  until  the  fatty 
acids  have  separated  on  top.     Cool,  break  the  cake  of 
fatty  acids  with  a  glass  rod,  pouring  off  the  aqueous  solu- 
tion.   Treat   the   acids   again   with   boiling   water,    cool, 
remove  to  a  porcelain  dish,  and  dry  at  100°  C.  until  freed 
from  all  traces  of  water. 

Two  to  three  grams  of  the  mixed  fatty  and  rosin  acids 
are  weighed  off  accurately  and  dissolved  in  a  flask  in  ten 
times  their  volume  of  absolute  alcohol,  and  a  current  of  dry 
hydrochloric  acid  gas  passed  through  for  about  forty-five 
minutes  or  until  the  gas  ceases  to  be  absorbed.  Allow 'to 
stand  one  hour,  then  dilute  it  with  five  times  their  volume 
of  water  and  boiled  until  clear.  From  this  point  the  analy- 
sis may  be  completed  volumetrically  or  gravimetrically. 

42.  Volumetrically.    The    contents    of    the    flask    are 
transferred  to  a  separatory  funnel  and  the  flask  rinsed  out 
several  times  with  ether.    After  vigorous  shaking  the  acid 
layer  is  run  off  and  the  remaining  ethereal  solution  contain- 
ing the  rosin  acids  washed  with  water  until  the  last  trace  of 
acid  is  removed.     Fifty  c.c.  of  alcohol  are  added  and  the 
solution    titrated    with    standard    caustic    potash,    using 
phenolphthalein   as   an   indicator.     The  rosin  acids  com- 
bine at  once  with  the  alkali,  whereas  the  ethylic  esters 
remain  unchanged.    The  number  of  c.c.  of  normal  alkali 
used  multiplied  by  0.346  will  give  the  amount  of  rosin  in 
the  sample. 

43.  Gravimetrically.    The    contents    of    the    flask    are 


SPECIAL  METHODS  ON  OIL  ANALYSIS.  61 

mixed  with  a  little  petroleum  ether,  boiling  below  80°  C., 
and  transferred  to  a  separating  funnel,  the  flask  being 
washed  out  with  the  same  solvent.  The  petroleum  ether 
layer  should  measure  about  50  c.c.  After  shaking,  the 
acid  solution  is  run  off  and  the  petroleum  ether  layer 
washed  once  with  water,  and  then  treated  in  the  funnel 
with  a  solution  of  0.5  gram  of  potassium  hydroxide  and 
5  c.c.  of  alcohol  in  50  c.c.  of  water.  The  ethylic  esters  dis- 
solved in  the  petroleum  ether  will  then  be  found  to  float 
on  top,  the  rosin  acids  having  been  extracted  by  the 
dilute  alkaline  solution  to  form  rosin  soap.  The  soap 
solution  is  then  run  off,  decomposed  with  hydrochloric 
acid,  and  the  separated  rosin  acids  collected  as  such,  or 
preferably  dissolved  in  ether  and  isolated  after  evaporat- 
ing the  ether.  The  residue,  dried  and  weighed,  gives  the 
amount  of  rosin  in  the  sample. 

44.  Determination  of  the  free  fatty  acids  in  linseed  oil. 
Ten  grams  of  oil  are  weighed  into  a  suitable  sized  Erlen- 
meyer  flask  and  50  c.c.  of  neutral,  aldehyde-free  alcohol 
added.  The  mixture  is  heated  to  about  60°  C.  for  a  minute 
or  two,  then  cooled  and  titrated  with  tenth-normal 
alcoholic  potash,  using  phenol phthalein  as  an  indicator. 

Oil  made  from  mouldy  seed,  or  seed  contaminated  with 
mustard  oil,  or  oil  containing  rosin,  will  have  a  high  acid 
figure.  Pure  raw  oil  should  have  a  low  acid  figure,  boiled 
oil  will  have  a  slightly  higher  figure. 

Free  mineral  acid  in  bleached  oil  is  determined  by 
washing  a  definite  weight  of  oil  with  water,  separating  the 
water,  and  titrating  the  dissolved  mineral  acid  present. 

Preparation  of  aldehyde,  free  alcohol  for  alcoholic  potash 
solution.  Dissolve  1.5  grams  of  silver  nitrate  in  about 
3  c.c.  of  water  and  add  to  a  litre  of  alcohol  in  a  glass-stop- 
pered cylinder,  mixing  thoroughly.  Dissolve  3  grams  of 
pure  potassium  hydroxide  in  10  to  15  c.c.  of  warm  alcohol. 


62  ANALYSIS   OF  MIXED  PAINTS. 

Cool,  pour  slowly  into  the  alcoholic  silver  nitrate  solution, 
without  shaking.  The  silver  oxide  is  precipitated  in  a 
finely  divided  condition.  Allow  to  stand  until  the  pre- 
cipitate has  completely  settled.  Siphon  off  the  clear 
liquid  and  distil.  The  distillate  will  be  neutral  and  free 
from  aldehydes,  and  will  not  darken  when  used  as  a  sol- 
vent for  potash. 

45.  Determination    of    the    saponification    value.     This 
value  is  also  spoken  of  as  the  Koettstorfer  number  and 
Saponification  number.     In  each  case  it  is  equivalent  to 
the  number  of  milligrams  of  potassium  hydroxide  neces- 
sary to  saponify  one  gram  of  the  oil. 

Two  grams  of  the  oil  are  weighed  out  into  a  small  Erlen- 
meyer  flask  and  saponified  with  25  c.c.  of  half-normal 
alcoholic  potash,  by  heating  gently  on  a  water  bath,  a 
funnel  being  inserted  in  the  flask.  When  the  saponification 
is  complete  a  few  drops  of  phenolphthalein  are  added  and 
the  excess  of  alkali  titrated  with  half-normal  hydrochloric 
acid.  A  blank  determination  of  the  strength  of  the 
alcoholic  potash  should  be  made  at  the  same  time. 

46.  Determination    of    the    flash    point    of    linseed    oil. 
For  exact  flash-point  figures,  rather  expensive  and  com- 
plicated testers  are  needed;  but  for  commercial  tests  that 
yield  approximately  the  same  figures,  a  very  simple  appa- 
ratus may  be  used,  consisting  of  a  two-ounce  crucible,  a 
thermometer  reading  at  least  300°  C.,  and  a  small  gas  jet 
attached  to  a  rubber  tube,  a  flame  about  the  size  of  a  pea 
being  used.    The  cup  is  filled  two-thirds  full  of  oil,  the 
bulb  of  the  thermometer    suspended  in  it,  and  the  oil 
slowly  heated.     The  determination  should   be  carried  on 
in  a  place  entirely  free  from  draughts.    At  short  intervals 
the  gas  flame  is  brought  close,  but  not  touching,  to  the 
surface  of  the  oil,  with  a  slow,  sweeping  motion.     The 
first  distinct  puff  of  pale  blue  flame  that  shoots  across  the 


SPECIAL  METHODS  ON  OIL  ANALYSIS.  63 

surface  of  the  oil  indicates  the  flash  point  of  the  oil,  and 
the  temperature  at  which  this  occurs  is  noted. 

47.  Hurst  states  that  linseed  oil,  whether  raw  or  boiled, 
flashes  about  243°  C. ;  but  these  figures  are  considerably 
lower  than  those  obtained  in  this  laboratory,  the  raw  oils 
flashing  in  the  vicinity  of  300°  C.,  and  the  pure  boiled  oils 
from  275°  to  300°  C.    Volatile  oils  used  in  the  drier  added 
to  the  oil,  lower  the  flash  point  considerably,  4  or  5  per 
cent  of  volatile  oil  lowering  the  flash  point  to  about  250°  C. 
The  other  vegetable  oils,  as  corn   and    cotton-seed  oils, 
flash  at  nearly  the  same  temperature  as  linseed  oil.     Min- 
eral oils,  such  as  would  be  used  for  adulteration,  flash  at 
193°  to  216°  C.,  rosin  oils  at  140°  to  167°  C.    The  presence 
of  rosin  oil  would  also  be  indicated  by  the  strong  odor  of 
rosin  given  off  during  the  heating.     Benzine  and  turpen- 
tine when  present  in  linseed  oil  rapidly  lower  the  flash 
point  according  to  the  percentage  present,  having  a  flash 
point  themselves  but  little  above  that  of  room  temperature. 

48.  Correction  to  be  applied  to  the  thermometer  reading. 

Let  N  =  Length  of  exposed  thread  of  mercury  expressed 

in  degrees. 

T  =  observed  boiling  point. 

t  =  temperature  of  the  auxiliary  thermometer,  the 
bulb  of  which  is  midway  between  ends  of 
the  exposed  mercury  thread. 

0.000154  =  apparent  coefficient  of  expansion  of  mercury 

in  glass. 
C  =  the  correction  in  degrees. 

Then    C  =  N  (T  -  t)  X  0.000154. 

49.  Evaporation  test.    This  test  will  show  very  closely 
the  amount  of  benzine  added  along  with  the  drier  in  the 
preparation  of  boiled  linseed  oil. 


64  ANALYSIS  OF  MIXED   PAINTS. 

Five  grams  of  the  oil  to  be  tested  are  weighed  into 
a  small  flat-bottomed  evaporating  dish  and  allowed  to 
remain  undisturbed  at  a  temperature  of  150°  C.  for  three 
hours.  The  dish  is  then  removed,  cooled  quickly,  and 
immediately  weighed.  The  loss  in  weight  represents 
usually  the  greater  portion  of  mineral  oils,  rosin  oils  or 
other  volatile  matters  present  in  the  sample. 

J.  Hortvet,  state  chemist  for  Minnesota,  states  that, 

"  Of  fifteen  samples  represented  as  raw  linseed  oil, 
when  subjected  to  this  test,  eleven  showed  no  loss  in 
weight,  while  four  gave  losses  amounting  to  less  than  0.3 
per  cent.  Of  one  hundred  and  ten  samples  represented 
as  boiled  oils,  sixty  gave  losses  above  2  per  cent,  thirty- 
two  showed  no  loss  in  weight,  and  of  the  remaining  eigh- 
teen the  loss  was  slight,  seldom  approaching  2  per  cent. 
Forty-seven  of  the  sixty  samples  which  gave  over  2  per  cent 
loss  were  found  to  vary  in  specific  gravity  from  0.8835  to 
0.9310.  All  samples  not  found  adulterated  by  the  usual 
tests  showed  a  specific  gravity  of  from  0.9310  to  0.9425, 
with  the  exception  of  one  sample  which  had  a  specific 
gravity  as  low  as  0.930,  but  by  the  other  tests  appeared 
to  be  straight  raw  linseed  oil." 

50.  Determination  of  flash  point  and  fire  test  of  petro- 
leum products,  turpentine,  etc.  Covered  testers.  New 
York  State  Board  of  Health  Tester.  This  instrument 
consists  of  a  copper  oil  cup  holding  about  10  ounces  heated 
in  a  water  bath  over  a  small  flame.  The  cup  is  provided 
with  a  glass  cover,  holding  a  thermometer.  This  cover 
also  has  a  hole  for  the  insertion  of  the  testing  flame. 

The  test  should  be  applied  as  follows :  * 

"  Remove  the  oil  cup  and  fill  the  water  bath  with  cold 
water  up  to  the  mark  on  the  inside.  Replace  the  oil  cup 

1  Report  New  York  State  Board  of  Health,  1882,  p.  495. 


SPECIAL  METHODS  ON  OIL   ANALYSIS.  65 

and  pour  in  enough  oil  to  fill  it  to  within  one-eighth  of  an 
inch  of  the  flange  joining  the  cup  and  the  vapor-chamber 
above.  Care  must  be  taken  that  the  oil  does  not  flow 
over  the  flange.  Remove  all  air  bubbles  with  a  piece  of 
dry  paper.  Place  the  glass  cover  on  the  oil  cup,  and  so 
adjust  the  thermometer  that  its  bulb  shall  be  just  covered 
by  the  oil. 

"If  an  alcohol  lamp  be  employed  for  heating  the  water 
bath,  the  wick  should  be  carefully  trimmed  and  adjusted 
to  a  small  flame.  A  small  Bunsen  burner  may  be  used  in 
place  of  the  lamp.  The  rate  of  heating  should  be  about 
two  degrees  per  minute,  and  in  no  case  exceed  three  degrees. 

"  As  a  flash  torch,  a  small  gas  jet  one-quarter  of  an 
inch  in  length,  should  be  employed.  When  gas  is  not  at 
hand  employ  a  piece  of  waxed-linen  twine.  The  flame 
in  this  case,  however,  should  be  small. 

51.  "  When  the  temperature  of  the  oil  in  the  case  of 
kerosene  has  reached  85°  F.,  the  testings  should  commence. 
To  this  end  insert  the  torch  into  the  opening  in  the  cover, 
passing  it  in  at  such  an  angle  as  to  well  clear  the  cover, 
and  to  a  distance  about  half-way  between  the  oil  and  the 
cover.  The  motion  should  be  steady  and  uniform,  rapid, 
and  without  any  pause.  This  should  be  repeated  at 
every  two  degrees'  rise  of  the  thermometer,  until  the  ther- 
mometer has  reached  95°,  when  the  lamp  should  be  re- 
moved and  the  testings  should  be  made  for  each  degree  of 
temperature  until  100°  is  reached.  After  this  the  lamp 
may  be  replaced  if  necessary,  and  the  testings  continued 
for  each  two  degrees. 

"  The  appearance  of  a  slight  bluish  flame  shows  that 
the  flashing  point  has  been  reached. 

"  In  every  case  note  the  temperature  of  the  oil  before 
introducing  the  torch.  The  flame  of  the  torch  must  not 
come  in  contact  with  the  oil. 


66  ANALYSIS  OF  MIXED  PAINTS. 

"  The  water  bath  should  be  filled  with  cold  water  for 
each  separate  test,  and  the  oil  from  a  previous  test  care- 
fully wiped  from  the  oil  cup." 

52.  Open  testers.     Tagliabue's  open  tester.    This  instru- 
ment is  similar  to  the  preceding,  except  that  it  is  smaller, 
the  oil  cup  being  of  glass  and   without  a  cover.     The 
water  bath  is  filled  as  before.     The  oil  cup  is  filled  to 
within  three-thirty-seconds  of  an  inch  of  the  top.     The 
heating  flame  is  regulated  to  three-fourths  of  an  inch  in 
height,  or  at  such  height  that  the  temperature  of  the  oil 
is  raised  two  and  a  half  degrees  per  minute  until  97°  F. 
is  reached,  when  the  test  flame  is  applied  and  the  testings 
made  every  two  degrees  until  the  flash  point  is  reached. 

53.  Fire  test.    The  fire  test  is  the  temperature  at  which 
an  oil  will  give  off  vapors,  which  when  ignited  will  burn 
continuously.    The  cover  is  removed  in  the  case  of  the 
closed  tester,  the  heating  being  continued  as  described 
above.    The  flame  may  be  extinguished  by  the  use  of  a 
piece  of  asbestos  board. 

54.  Specifications  for  various  oils.     It  often  devolves 
upon  the  paint  chemist  to  examine  various  oils,  some  of 
which  cannot  be  considered  as  paint  oils,  hence  the  follow- 
ing specifications  adopted  by  the  Treasury  Department  at 
Washington,  1907,  of  various  oils  will  be  of  interest. 

55.  Linseed  oil.     It  must  be  thoroughly  strained  and 
settled,  transparent,  free  from  suspended  matter,  and  have 
the  properties  of  a  well-aged  oil.    The  oil  shall  conform  to 
the  following  physical  and  chemical  tests:  specific  gravity 
at  15.5°  C.,  not  less  than  .933;  flash  point  (open  cup)  not 
less  than  280°  C.;  viscosity  at  20°  C.,  as  determined  by 
Engler  viscosimeter  (water  being  100),  not  less  than  750; 
iodine  absorption  number  as  determined  by  Wijs'  method 
(time  of  absorption  2  hours),  not  less  than  175;  to  be 
entirely  free  of  all  acids  except  fatty  acids,  of  which  not 


SPECIAL  METHODS  ON  OIL  ANALYSIS,  67 

more  than  2  per  cent  calculated  as  linolic  acid  should  be 
present;  when  heated  to  300°  C.,  and  allowed  to  cool,  the 
oil  should  show  no  suspended  matter  or  deposit ;  and  must 
show  excellent  drying  qualities,  as  demonstrated  by  the 
Livache  method. 

56.  Deodorized  benzine.     Should  be  a  purified  petroleum 
distillate,  free  from  sulphur;  specific  gravity  between  .725 
and  .735  at  15.5°  C. 

57.  Engine  oil.     Free  running  oil  is  required,  consist- 
ing of  90  per  cent  refined  petroleum,  and  10  per  cent  pure 
acidless  lard  oil.    The  specific  gravity  should  not  be  less 
than  .905  at  15.5°  C.;  viscosity  by  Engler  viscosimeter 
should  not  be  less  than  1550,  and  flash  point  less  than 
200°  C.     Samples  that  comply  with  the  above   require- 
ments will  be  subjected  to  a  practical  test. 

58.  High  pressure  cylinder  oil.     An  oil  is  required  con- 
sisting of  90  per  cent  refined  petroleum  stock  and  10  per 
cent  of  acidless  tallow;  specific  gravity  should  not  be  less 
than  .870  at  50°  C.;  flash  point  not  less  than  285°  C.;  vis- 
cosity by  Engler  viscosimeter  should  not  be  less  than  2000 
at  50°  C.,  and  not  less  than  350  at  97°  C.    The  mixture 
should  be  neutral,  free  from  adulterations,  and  suitable 
for  use  on  engine  cylinders  with  steam  pressure  of  125 
pounds  per  square  inch.     Samples  that  comply  with  the 
above  requirements  will  be  subjected  to  a  practical  test. 

59.  Lithographic  varnish.     No.  0.     Should  be  a  varnish 
of  the  best  quality  of  linseed  oil  and  with  a  specific  gravity 
of  .940  at  25°  C.,  and  be  suitable  for  making  fine  typo- 
graphic inks. 

No.  1.  Requirements  same  as  for  No.  0,  but  with  a 
specific  gravity  of  .945  at  25°  C. 

No.  3.  Requirements  same  as  for  No.  0,  but  with  a 
specific  gravity  of  .965  at  25°  C. 

60.  Kerosene  oil.   Under  this  specification  is  required 


68  ANALYSIS  OF  MIXED  PAINTS. 

refined  petroleum,  water  white,  specific  gravity  .790  to 
.810  at  15.5°  C.,  and  flash  point  not  lower  than  45°  C. 

61.  Lard  oil.     Should  contain  the  least  possible  quantity 
of  free  acid ;  should  show  a  cold  test  of  not  over  4°  C. ;  be 
free  from  adulterations,  and  have  specific  gravity  of  .914  to 
.916  at  15.5°  C.    The  oil  should  be  made  from  fresh  lard, 
be  free  from  admixture  with  other  oils,  and  should  respond 
to  no  test  for  cotton-seed  oil. 

62.  Sperm  oil.    Should  be  pure  winter-strained  sperm 
oil,  free  from  admixtures  of  any  kind;  specific  gravity  to  be 
.875  to  .884  at  15.5°  C.,  and  flash  point  250°  C.;  viscosity 
as  determined  by  Engler  viscosimeter  to  be:  at  20°  C.,  not 
less  than  495;  at  50°  C.,  not  less  than  220;  and  at  90°  C., 
not  less  than  133. 

63.  Gasoline.    Should  be  a  refined  petroleum  product 
of  .680  to  .705  specific  gravity  at  15.5°  C. 


CHAPTER  V. 

ANALYSIS  OF  WHITE  LEAD. 

64.  Color.    The  two  samples  are  weighed  out  in  gram 
lots  on  to  a  large  glass  plate,  twelve  drops  of  bleached 
linseed  oil  added  to  each  and  rubbed  up  thoroughly,  and 
matched  up  on  a  microscope  slide,  the  color  being  judged 
from  both  sides  of  the  glass.     After  comparing  the  color, 
place  the  slide  in  the  steam  oven  for  two  hours.    This 
will  give  some  idea  as  to  the  amount  of  yellowing  that 
will  occur  when  the  lead  is  used  in  painting.    This  defect 
is  particularly  marked  in  pulp  leads. 

65.  Lead  acetate.    The  presence  of  lead  acetate  may  be 
detected  by  pouring  a  few  drops  of  a  10  per  cent  solution 
of  potassium  iodide  upon  the  dry  lead.     If  it  turns  yellow 
it  contains  acetate,  wrhile  a  well-washed  sample  will  remain 
unchanged. 

66.  Opacity.    Two    grams    each    of    the    sample    and 
standard  are  very  carefully  rubbed  up  with  .01  gram  of 
ultramarine  blue  and  twenty-four  drops  of  oil  as  described 
under  the  section  on  the  Determination  of  the  Tinting 
Strength  of  Colors.    The  more  strongly  the  lead  is  colored, 
the  weaker  it  is  in  hiding  power  or  opacity.    Adding 
we\q;hed  amounts  of  lead  until  the  colors  are  of  equal 
depth  will  show  the  ratio  between  the  two. 

67.  Painting  test.    The  painting  value  is  best  judged 
by  painting  test  boards  as  described  under  the  section  on 
the  Comparison  of  Paints  for  Covering  Power,  and  after- 
wards exposing  them  under  suitable  conditions. 

68.  Sandy  lead.    One  hundred  grams  of  the  paste  lead 
are  thinned  with  benzine  and  run  through  a  fine  bolting 

69 


70  ANALYSIS  OF  MIXED   PAINTS. 

cloth,  thoroughly  stirred,  and  allowed  to  settle  slightly 
for  a  short  time  only.  The  benzine  portion  is  decanted 
and  the  sediment  washed  with  benzine  in  a  similar  man- 
ner, until  the  benzine  comes  off  nearly  clear,  leaving  the 
sand  alone  as  a  residue.  Sandy  lead,  while  present  in 
nearly  all  commercial  lead,  should  be  below  2J  per  cent, 
but  will  sometimes  be  present  in  quantities  as  large  as  10 
per  cent. 

69.  Foreign  .pigments.     White  lead  is  often  adulterated 
with  less  expensive   pigments,  such  as    barytes    (barium 
sulphate),  zinc  oxide,  calcium  carbonate,  calcium  sulphate, 
and  the  various  kinds  of  silicates.     On  treating  a  small 
portion  of  the  sample  with  acetic  acid  and  diluting,  the 
white  lead  and  calcium  salts  will  go  into  solution,  leaving 
any  lead    sulphate,    barytes,   silica    and    silicates   undis- 
solved.     Barytes  is  tested  for  by  the  flame  test.     Zinc  is 
recognized   by  adding  a   few  drops   of   potassium   ferro- 
cyanide  to  a  portion  of  the  clear  acetic  acid  solution,  a 
whitish  precipitate  of  zinc   ferrocyanide  being  obtained. 
Hydrogen  sulphide  is  passed  through  the  remainder  of  the 
acetic  acid  solution  until  all  of  the  lead,  and  any  zinc,  are 
precipitated.     Filter,  and  treat  the  filtrate  with  ammo- 
nium oxalate  and  leave  in  a  warm  place.     A  white  precipi- 
tate indicates  the  presence  of  calcium  compounds. 

If  the  white  lead  is  found  to  contain  other  pigments, 
the  analysis  is  conducted  as  described  under  Analysis  of 
White  Paints. 

70.  Estimation    of    carbon    dioxide.    The    amount    of 
carbon  dioxide  in  white  lead  may  be  estimated  easily  and 
accurately  by  means  of  Knorr's  Apparatus  or  Scheibler's 
Apparatus. 


ANALYSIS  OF  WHITE  LEAD. 
KNORR'S    APPARATUS. 


71 


(1)  Description  of  apparatus.  This  apparatus  (Fig.  4) 
employs  only  ground-glass  joints,  and  may  be  quickly 
made  ready  for  use  or  taken  to  pieces  and  packed  away. 


FIG.  4.  —  KNORR'S  APPARATUS. 

On  the  other  hand,  it  is  inflexible  and  must  be  carefully 
handled.  A  is  distilling  flask  fitted  to  condenser  by  a 
ground-glass  stopper;  B,  reservoir  containing  acid;  C, 
soda-lime  tube;  D,  condenser;  E,  calcium  chloride  tube; 
F,  U-»tube  filled  with  pumice  stone  moistened  with  sul- 
phuric acid,  followed  by  a  calcium-chloride  tube  G.  The 
three  soda-lime  tubes  H,  H,  H  are  followed  by  a  calcium 
chloride  tube  K,  which  is  connected  with  an  aspirator 
at  L. 

The  calcium  chloride  and  soda  lime  employed  should  be 
finely  granulated  and  freed  from  dust  with  a  sieve. 

71.  One  gram  of  the  sample  to  be  examined  is  placed  in 
the  distilling  flask,  which  must  be  perfectly  dry.  The 
flask  is  closed  with  a  stopper  carrying  the  tube  connecting 
with  the  absorption  apparatus  and  also  with  the  funnel 
tube.  The  tubes  in  which  the  carbon  dioxide  is  to  be 
absorbed  are  weighed  and  attached  to  the  apparatus.  In 
case  two  Liebig  bulbs  are  employed,  one  for  potassium 


72  ANALYSIS  OF  MIXED  PAINTS. 

hydroxide  and  the  other  for  sulphuric  acid,  to  absorb  the 
moisture  given  up  by  the  potassium  hydroxide  solution,  it 
will  be  necessary  to  weigh  them  separately.  If  soda-lime 
tubes  are  employed  it  will  be  found  advantageous  to  weigh 
them  separately  and  fill  the  first  tube  anew  when  the 
second  tube  begins  to  increase  in  weight  materially.  The 
tube  B  is  nearly  filled  with  hydrochloric  acid  (sp.  gr.  1.1), 
and  the  guard  tube  C  placed  in  position.  The  aspirator 
is  now  started  at  such  a  rate  that  the  air  passes  through 
the  Liebig  bulbs  at  the  rate  of  about  two  bubbles  per 
second.  The  stopper  of  the  funnel  tube  is  opened  and  the 
acid  allowed  to  run  slowly  into  the  flask,  care  being  taken 
that  the  evolution  of  the  gas  shall  be  so  gradual  as  not  to 
materially  increase  the  current  through  the  Liebig  bulb. 
After  the  acid  has  all  been  introduced,  the  aspiration  is 
continued,  when  the  contents  of  the  flask  are  gradually 
heated  to  boiling,  the  bulb  in  tube  B  being  closed.  While 
the  flask  is  being  heated  the  aspirator  tube  may  be  removed, 
although  many  analysts  prefer  when  using  ground-glass 
joints  to  aspirate  during  the  entire  operation.  The  boiling 
is  continued  for  a  few  minutes  after  the  water  has  begun 
to  condense  in  D,  when  the  flame  is  removed,  the  valve  in 
the  tube  B,  opened,  and  the  apparatus  allowed  to  cool  with 
continued  aspiration.  The  absorption  tubes  are  then 
removed  and  weighed,  the  increase  in  weight  being  due  to 
carbon  dioxide. 

72.  Scheibler's  apparatus.  One-half  gram  of  the  sample 
is  weighed  into  the  flask  A  (see  illustration),  and  10  c.c. 
of  dilute  hydrochloric  acid  (sp.  gr.  1.1)  pipetted  into  the 
globe  funnel  M.  A  considerable  number  of  glass  beads 
should  be  added  to  the  flask. 

The  stop-cock  G  is  opened  and  the  water  in  F  forced  up 
into  the  tubes  L  and  N  by  pressing  on  the  bulb  H.  Bring 
the  water  slightly  above  the  zero  mark  at  the  top,  and  by 


ANALYSIS   OF  WHITE   LEAD. 


73 


opening  the  pinch-cock  0  bring  the  water  in  the  tubes  to 
a  level  on  the  zero  mark. 

The  apparatus  is  now  ready  for  the  determination. 
Open  the  stop-cock  B  and  allow  the  acid  to  flow  slowly 
into  the  flask.  The  gas  immediately  begins  to  come  off 
and  pass  into  the  rubber  balloon  E,  which  causes  the  water 


FIG.  5. — SCHEIBLER'S  APPARATUS. 

in  AT  to  be  depressed  and  that  in  L  to  be  correspondingly 
elevated.  The  pinch-cock  G  is  opened  and  the  water  in  L 
is  allowed  to  flow  out  sufficiently  fast  to  keep  L  and  N  as 
nearly  on  the  same  level  as  possible.  When  the  water 


74  ANALYSIS  OF  MIXED   PAINTS. 

ceases  to  be  depressed  in  N,  the  pinch-cock  G  is  closed 
and  the  apparatus  allowed  to  stand  five  minutes,  then  the 
flask  A  is  shaken  three  times  at  suitable  intervals.  At  the 
end  of  half  an  hour  all  of  the  carbon  dioxide  should  be 
expelled.  The  water  in  the  tubes  is  brought  to  the  same 
level  and  the  burette  reading  made.  A  barometer  reading 
should  also  be  taken  and  the  temperature  of  the  ther- 
mometer on  the  instrument  noted  in  order  to  correct  for 
pressure  and  temperature.  By  referring  to  the  following 
tables  the  per  cent  of  carbon  dioxide  may  be  easily  cal- 
culated. 

EXAMPLE. 

Weight  of  sample 0.5  gram. 

Burette  reading 30.3  c.c. 

Barometer  reading 750.  m.m. 

Thermometer  reading 24°  C. 

Correction  for  absorption    .    .    . 5. 09  c.c. 

Gas  evolved  .  30.30  c.c. 


Total  gas  liberated 35. 39  c.c. 

Weight  of  1  c.c.  of  carbon  dioxide  at  750  m.m.  pressure 
and  24°  C.  =  .001731  g. 

35.39  X  .001731  =  .06126  g. 
0.5  :  0.06126  :  :  100  :  x 
x  =--  12.25  per  cent  carbon  dioxide  in  sample. 

NOTE.  —  In  determining  the  amount  of  carbon  dioxide  in  such 
products  as  "mineral  primer"  made  from  dolomitic  limestone,  the 
evolution  of  carbon  dioxide  is  incomplete  without  boiling. 


ANALYSIS   OF  WHITE  LEAD. 


75 


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76 


ANALYSIS  OF  MIXED   PAINTS. 


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ANALYSIS    OF  WHITE    LEAD. 


77 


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78  ANALYSIS   OF   MIXED   PAINTS. 

75.  ANALYSES  OF  WHITE   LEADS   BY  AUTHOR. 


No. 

Sample. 

Sandy 
Lead. 

Carbon 
Dioxide. 

Lead  Hy- 
droxide. 

LeadCar- 
bonate. 

I. 
II. 
III. 

Old    Dutch    Process 
White  Lead     .    .    . 
Old     Dutch     Process 
White  Lead     .    .    . 
Quick  Corrosion  White 
Lead     .    .    . 

6.25 
9.13 

11.3,5 
11.63 
11  26 

31.11 
29.41 
31  65 

68.89 
70.59 

f\Q     OK 

IV. 

Kremnitz,  White  Lead 

10.93 

33.65 

66.35 

76.  Determination  of  acetic  acid  in  white  lead.     Thomp- 
son's method.    Eighteen  grams  of  the  dry  white  lead  are 
placed  in  a  500  c.c.  flask,  this  flask  being  arranged  for  con- 
nection with  a  steam  supply,  and  also  with  an  ordinary 
Liebig  condenser.     To  this  white  lead  is  added  40  c.c.  of 
syrupy  phosphoric  acid,  18  grams  of  zinc  dust,  and  about 
50  c.c.  of  water.    The  flask  containing  the  material  is 
heated  directly  and  distilled  down  to  a  small  bulk.     Then 
the  steam  is  passed  into  the  flask  until  it  becomes  about 
half  full  of  condensed  water,  when  the  steam  is  shut  off 
and  the  original  flask  heated  directly  and  distilled  down 
to  the  same  small  bulk  —  this  operation  being  conducted 
twice.    The  distillate  is  then  transferred  to  a  special  flask 
and  1  c.c.  of  syrupy  phosphoric  acid  added  to  insure  a 
slightly  acid  condition.     The  flask  is  then  heated  and  dis- 
tilled down  to  a  small  bulk,  say  20  c.c.     Steam  is  then 
passed  through  the  flask  until  it  contains  about  200  c.c.  of 
condensed  water,  when  the  steam  is  shut  off  and  the  flask 
heated  directly. 

77.  These  operations  of  direct  distillation  and  steam 
distillation  are  conducted   until   10  c.c.   of  the  distillate 

N 
require  but  a  drop  of   rr  alkali  to   produce  a  change   in 


ANALYSIS   OF   WHITE   LEAD. 


79 


the  presence  of  phenolphthalein.     Then  the  bulk  of  the 

N 
distillate   is  titrated  with  ^  sodium  hydroxide,  and  the 

acetic  acid  calculated.  It  will  be  found  very  convenient 
in  this  titration,  which  amounts  in  some  cases  to  600-700 
c.c.,  to  titrate  the  distillate  when  it  reaches  200  c.c.,  and 
so  continue  titrating  every  200  c.c.  as  it  distils  over. 

If  the  dry  white  lead  under  examination  has  been 
obtained  by  extraction  as  a  residue  from  white  lead  paste, 
it  is  well  that  this  extraction  should  be  exceedingly 
thorough,  as,  otherwise,  fatty  acids  may  be  held  and  dis- 
tilled with  the  acetic  acid.  Even  then  they  will  not  inter- 
fere with  the  final  titration,  as  they  may  be  filtered  from 
the  distillate  before  titration,  should  that  be  desired. 

78.   ANALYSES  OF  MISCELLANEOUS  WHITE   LEADS   MADE 
BY  THE  AUTHOR. 


No. 

Net 

Weight. 

White 
Lead. 

Lead 
Sul 
phate. 

Zinc 
Oxide. 

Barytes 

Calcium 
Car- 
bonate. 

Silica. 

Clay. 

Unde- 
ter- 
mined. 

I. 
II. 
III. 

IV. 
V. 
VI. 

13  .5  oz. 
15.4oz. 
14.8oz. 
IS.Ooz. 

1  ib. 

9.98 
64.73 
4.69 
3.34 
54.69 

3^29 

12.00 
3.60 
12.50 
8.96 
17.38 
6.90 

76.28 
30.43 
75.72 
72.35 
25.57 
89.81 

5.89 
4.52 

1.10 
0.76 
0.67 

10^83 

0.64 
0.48 
0.53 

oise 

VII. 

14.2oz. 
lib. 

10.69 

20.03 

69.28 

VIII. 

14  oz. 
15  oz. 

5.31 

6.37 

13.68 

74.25 

•  •  • 

0.39 

None  of  the  above  products  are  entitled  to  be  called 
white  lead.  Only  one  bore  the  name  of  the  company 
putting  out  the  product. 

79.  Short  weights  of  white  lead  packages.  All  the  white 
leads  and  so-called  white  leads,  examined  by  the  writer, 
have  been  found  to  be  short  weight.  That  is,  the  kegs 


80 


ANALYSIS  OF  MIXED   PAINTS. 


supposed  to  contain  12J  pounds  will  actually  contain  in 
each  eight  kegs,  which  should  have  shown  100  pounds, 
only  83  to  89  pounds.  As  showing  to  what  extent  the 
different  so-called  white  leads  actually  varied  and  fell  short 
in  weight,  I  give  the  following  list. 


Number. 

Assumed 
Weight. 

Net 
Weight. 

I 

Lbs. 
50 

Lbs.     Oz. 

46          0 

II 

124 

11         13 

III    . 

124 

10           6 

IV 

124 

10          7 

V 

25 

21         12 

VI 

25 

22           7' 

VII     

124 

10          0 

VIII               .           

124 

11           0 

CHAPTER  VI. 

ANALYSIS    OF    SUBLIMED    LEAD,  ZINC   OXIDES  AND   ZINC- 
LEAD   PIGMENTS. 

Analysis  of  Sublimed  Lead.1 

So.  Lead  and  zinc  oxide.  Weigh  one  gram  into  a  small 
beaker,  add  20  c.c.  of  10  per  cent  sulphuric  acid,  stir  well 
and  allow  to  stand  10  minutes,  filter,  wash  slightly  with 
dilute  sulphuric  acid  on  filter. 

Residue.  Dissolve  through  filter  with  hot,  slightly  acid 
ammonium  acetate  solution,  wash  with  hot  water,  dilute 
to  200  c.c.  with  hot  water.  Add  slight  excess  of  potassium 
bichromate  solution  and  heat.  Filter  on  Gooch  crucible, 
wash  with  water.  Dry,  ignite  and  weigh  as  lead  chromate. 

Filtrate.  Add  about  2  grams  of  ammonium  chloride, 
heat  to  boiling,  add  excess  of  ammonia  and  filter.  Reject 
residue.  Add  1  gram  of  microcosmic  salt  and  a  very  slight 
excess  of  acetic  acid.  Boil,  cool,  filter  on  Gooch  crucible, 
and  wash  with  water.  Ignite  and  weigh  as  zinc  pyrophos- 
phate.  Calculate  to  zinc  oxide. 

81.  Sulphates.  Dissolve  0.5  gram  in  water  25  c.c., 
ammonia  10  c.c.,  hydrochloric  acid  in  slight  excess. 

Dilute  to  200  c.c.  and  add  a  piece  of  aluminum  foil  which 
should  about  cover  the  bottom  of  the  beaker.  It  is  impor- 
tant that  this  be  held  at  the  bottom  by  a  glass  rod.  Boil 
gently  until  the  lead  is  precipitated.  Completion  of  this 
is  shown  by  the  lead  ceasing  to  coat  or  cling  to  the  alumi- 

r  The  author  is  indebted  to  L.  S.  Hughes  of  the  Picher  Sublimed 
Lead  Company  for  this  method. 

81 


82  ANALYSIS   OF  MIXED   PAINTS. 

num.  Decant  through  a  filter,  pressing  the  lead  sponge 
into  a  cake  to  free  it  from  solution.  Add  to  filtrate  a  little 
sulphur-free  bromine  water,  boil  and  precipitate  as  barium 
sulphate  in  the  usual  manner. 

82.   Sulphur  dioxide.     Treat  two  grams  with  5  per  cent 

N 
sulphuric    acid   and    tritrate    with  -^-r  iodine.     A    quick 


method  of  calculating  the  lead  sulphate  and  oxide  from 
the  above  data  is  the  following  :  Multiply  the  weight  of 
barium  sulphate  from  one  gram  by  1.3,  which  gives  the 
weight  of  lead  sulphate.  Multiply  the  same  weight  of 
barium  sulphate  by  0.888  and  deduct  this  result  from  the 
total  lead  found.  Multiply  the  difference  by  1.077,  which 
will  give  the  lead  oxide. 

83.  Composition  of  sublimed  lead.  The  approximate 
composition  of  sublimed  lead  as  stated  by  the  manufac- 
turers is  as  follows:- 

Per  cent. 
Lead  sulphate  ..................         75 

Lead  oxide     ...................         20 

Zinc  oxide      ...........    '.    .......  5 

100 

the  lead  sulphate  and  lead  oxide  being  apparently  com- 
bined as  a  white  oxysulphate.  The  zinc  oxide  is  inciden- 
tal to  the  manufacture. 

ANALYSES  OF  SUBLIMED  LEAD  BY  THE  AUTHOR. 

I.  II. 

Per  cent.      Per  cent. 

Lead  sulphate  ...........  75.02  80.29 

Lead  oxide     ..........    .    .  18.48  14.46 

Zinc  oxide      ............  6.22  5.18 

Silica,  alumina,  and  ferric  oxide    ...  0  .  28  .07 


100.00  100.00 


ANALYSIS  OF  SUBLIMED  LEAD.         83 

The  Identification  and  Estimation  of  Sublimed  White 
Lead  in  Mixtures.1 

84.  Neutral    ammonium   chloride  solution  will  dissolve 
the    lead    compounds   of    sublimed  white  lead;  also    the 
hydrate  of  corroded  white  lead,  zinc  oxide,  and  some  cal- 
cium sulphate.     It  leaves  undissolved  calcium  carbonate, 
zinc  sulphide,  normal  lead  carbonate,  and  the  content  of 
lead  carbonate  in  corroded  lead. 

To  determine  the  sublimed  white  lead  in  a  pigment 
containing  the  above  ingredients,  boil  the  sample  with  a 
considerable  excess  of  strong  neutral  ammonium  chloride 
solution,  filter  hot  on  the  pump,  and  wash  with  hot  dilute 
neutral  ammonium  chloride. 

85.  The  lead,  zinc,  lime  and  sulphuric  anhydride  are 
determined  in  the  filtrate.     The  required  sulphur  trioxide 
is  combined  with  the  lime,  and  the  rest  with  the  lead.    Any 
excess  of   lead  is  contingent  in  its  application  upon   the 
amount   of   lead    found   undissolved   by  the   ammonium 
chloride. 

If  there  is  an  appreciable  amount  of  this  residual  car- 
bonate, the  required  hydrate  is  calculated,  and  a  deduc- 
tion made  from  the  excess  lead  found  in  the  filtrate.  Any 
lead  in  the  original  filtrate  not  satisfied  is  now  calculated 
to  lead  oxide  and  regarded  as  the  lead  oxide  of  sublimed 
white  lead,  and  the  lead  sulphate  and  zinc  oxide  thereof 
calculated  and  deducted  from  the  total  of  these  com- 
pounds. 

It  will  be  noted  that  the  conditions  above  considered 
are  much  more  complex  than  need  be  anticipated  in  the 
analysis  of  actual  paints. 

Extraction  of  lead  sulphate  by  the  above  treatment 
prevents  the  necessity  of  considering  the  sulphuric  anhy- 
1  The  author  is  indebted  to  L.  S.  Hughes  for  this  method. 


84  ANALYSIS  OF  MIXED  PAINTS. 

dride  of  possible  barium  sulphate,  and  leaves  the  original 
residue  in  such  shape  that  if  it  contains  both  the  car- 
bonate and  sulphate  of  barium  they  can  be  conveniently 
separated. 

Analysis  of  Zinc  Oxides,  Leaded  Zincs,  and  Zinc- 
Lead  Whites. 

86.  Moisture.    Heat  2  grams  at  105  °C.  for  3  hours, 
cool  and  weigh. 

87.  Sulphur  dioxide.    Weigh  2  grams  into  a  250  c.c. 
beaker,  add  100  c.c.  of  distilled  water  that  has  been  freshly 
boiled  and  cooled,  and  5  c.c.  of  concentrated  sulphuric 
acid;  allow  to  stand  15  minutes.    Titrate  with  standard 
hundredth  normal  iodine  solution,  using  starch  paste  as 
an  indicator. 

1  c.c.  hundredth  normal  iodine  =  .001269  grams  iodine. 

Wt.  iodine  X  0.252  =  wt.  sulphur  dioxide. 

The  presence  of  sulphur  dioxide  in  appreciable  amounts 
in  zinc  oxide  pigments  should  be  considered  highly  unde- 
sirable, as  it  tends  to  cause  the  manufactured  paint  to 
harden  in  the  package. 

Preparation  of  reagents.  Iodine  solution.  Dissolve 
12.685  grams  of  pure  iodine  and  about  18  grams  of  potas- 
sium iodide  in  about  150  c.c.  of  water  in  a  graduated  litre 
flask.  After  solution,  fill  to  the  mark  with  water  that 
has  been  freshly  boiled. 

Sodium  thiosulphate.  Dissolve  25  grams  in  a  litre  of 
water  that  has  been  freshly  boiled. 

Starch  paste.  One  gram  of  starch  is  boiled  in  200  c.c. 
of  distilled  water. 

Standardizing  the  sodium  thiosulphate  solution.  Place 
20  c.c.  of  standard  potassium  bichromate  solution  in  a  glass- 
stoppered  flask,  add  10  c.c.  of  a  15  per  cent  solution  of 
potassium  iodide.  Add  to  this  5  c.c.  of  strong  hydro- 


ANALYSIS  OF  SUBLIMED  LEAD.  85 

chloric  acid.  Allow  the  solution  of  sodium  thiosulphate 
to  flow  slowly  into  the  flask  until  the  yellow  color  has 
almost  disappeared.  Add  a  few  drops  of  starch  paste, 
and  with  constant  shaking,  continue  to  add  the  sodium 
thiosulphate  until  the  blue  color  just  disappears. 

88.  Zinc   sulphate.     Zinc    oxide   not    being   soluble    in 
less  than  one  million  parts  of  water,  according  to  Comey; 
any  zinc  sulphate  present  may  be  dissolved  out.     Weigh 
5  grams  on  to  a  filter,  add  20  c.c.  of  hot  water,  repeat  with 
two  more  additions.     Titrate  the  hot  filtrate  with  ferro- 
cyanide  of  potash  after  making  acid   with  acetic  acid. 
Calculate  soluble  zinc  to  zinc  sulphate.    The  zinc  oxide 
should  not  be  subjected  to  a  prolonged  boiling,  owing  to 
possible  interaction  between  the  lead  sulphate  and  zinc 
oxide. 

89.  Insoluble  matter.     Dissolve   1  gram  in  20  c.c.   of 
strong  hydrochloric  acid,  add  50  c.c.  of  water,  boil   10 
minutes    more.     Filter,    wash    with    boiling    hot    water, 
ignite,  and  weigh.     Unless  the  sample  is  adulterated,  the 
insoluble  matter  is  usually  reported  as  silica. 

90.  Lead.    To  filtrate  from  89,  add  3  c.c.  of  concen- 
trated sulphuric  acid,  stir  and  evaporate  until  white  fumes 
of  sulphur  trioxide  appear.     Cool,  add  30  c.c.  water  to 
dissolve    the    zinc    sulphate,  warm,  add   50  c.c.  alcohol, 
allow  to  stand  one-half  hour,  filter  on  Gooch  crucible, 
washing  first  with  water  containing  2  per  cent  of  sulphuric 
acid,  finish    washing    with    50    per    cent   alcohol.     Dry, 
ignite  over  ordinary  lamp  for  two  or  three  minutes,  at 
low  red  heat,  and  weigh  as  lead  sulphate. 

91.  Sulphuric    acid.     Dissolve  0.5  gram  of  pigment  in 

Water  25  c.c. 

Ammonia  10  c.c. 

Hydrochloric  acid  in  slight  excess. 


86  ANALYSIS  OF  MIXED   PAINTS. 

Dilute  to  200  c.c.  and  add  a  piece  of  aluminum  foil,  which 
should  about  cover  the  bottom  of  the  beaker.  It  is  impor- 
tant that  this  be  held  at  the  bottom  by  a  glass  rod.  Boil 
gently  until  the  lead  is  precipitated.  Completion  of  this 
is  shown  by  the  lead  ceasing  to  coat  or  cling  to  the  alum- 
inum. Decant  through  a  filter,  pressing  the  lead  sponge 
into  a  cake  to  free  it  from  solution.  Add  to  filtrate  a 
little  sulphur- free  bromine  water,  boil  to  expel  bromine, 
add  15  c.c.  of  barium  chloride,  boil  10  minutes,  filter, 
wash  with  hot  water,  ignite  and  weigh  as  barium  sulphate, 
calculate  to  sulphur  trioxide  by  multiplying  by  0.3433. 

92.  Zinc  oxide.     To  the  filtrate  from  90,  which  contains 
the  zinc,  evaporate  excess  of  alcohol,  add  sodium  carbon- 
ate in  excess,  boil,  settle,  decant  several  times  on  to  filter, 
in  order  to  remove  the  sodium  salts,  and  finally  wash 
thoroughly  with  hot  water.     Dry,  and  remove  precipitate 
as  free  as  possible  from  filter  paper.     Ignite  filter  in  a 
weighed   porcelain  crucible  and  cool.    Add  the   precipi- 
tate, ignite  gently  at  first,  and  then  at  red  heat  to  constant 
weight,  weigh  as  zinc  oxide.     If  desired  the  zinc  may  be 
estimated  volumetrically,  as  described  under  the  analysis 
of  white  paints. 

93.  Calculations.     Deduct  the  sulphuric  .acid  combined 
with  the  zinc  as  zinc  sulphate  from  the  total  combined 
sulphuric  acid.     Calculate  the  remainder  to  lead  sulphate 
by    multiplying    the    combined    sulphuric    acid    (sulphur 
trioxide)  by  3.78.     Deduct  the  calculated  lead  sulphate 
from  the  total  lead  which  was  weighed  as  sulphate,  and 
calculate  the  remaining  lead  to  lead  oxide  by  multiplying 
the  lead  sulphate  by  0.7359.     Calculate  the  zinc  sulphate 
to  zinc  oxide  by  multiplying  by  0.503,  and  deduct  from  total 
zinc  oxide.    The  difference  is  the  zinc  oxide  in  the  sample. 

94.  Classification.     For  convenience  the  American  zincs 
may  be  divided  into  the  following  classes: 


ANALYSIS  OF  SUBLIMED  LEAD.         87 

1.  Green  seal  and   Florence  red  zinc  oxides,  which  are 
similar  to  the  imported  zinc  oxides,  being  made  by  the 
sublimation  of  the  metal  itself,  and  hence  constitute  the 
purest  types  of  zincs. 

2.  New    Jersey  zinc   oxides ,    made  directly    from   the 
Franklinite  ore.    These  zinc  oxides,  while  not  as  white 
as  those  sublimed  from  metallic  zinc,  are  very  pure,  usually 
running    over    99    per    cent    zinc    oxide.     The    following 
analyses  *  are  representative  of  this  class  of  zincs : 

I.  II. 

Moisture 0.03  0.06 

Silica,  etc 0.08  0.19 

Zinc  sulphate 0.11  0.15 

Lead  sulphate 0.03  02 

Zinc  oxide •      99.75  99.58 

100.00  100.00 

3.  Mineral  Point  zincs,  manufactured  at  Mineral  Point, 
Wisconsin;  these  contain  a  varying  amount  of  lead  sul- 
phate and  usually  appreciable  amounts  of  zinc  sulphate 
as  shown  in  the  following  analyses.1 

I.  II. 

Sulphur  dioxide ...  trace 

Lead  sulphate 4.22  5.98 

Zinc  sulphate 1.41  0.61 

Silica 0.06  0.05 

Zinc  oxide 94.31  93 . 36 

100.00  ~ 100. 00 

4.  Leaded  zincs,  made  in  Missouri  and  Kansas,  which 
contain  a  much  larger  percentage  of  lead  sulphate  than 
the  Mineral  Point  zincs. 

ANALYSES   OF  LEADED  ZINCS   BY  THE  AUTHOR. 

I.  II.  III. 

Moisture     ........             0.03  0.02  0.04 

Sulphur  dioxide 0.30  0.29  0.50 

Zinc  sulphate 0.86  1.49  1.26 

Lead  sulphate 26.46  19.76  23.06 

Zinc  oxide 72.11  78.11  74.72 

Undetermined 0.24  0.33  0.42 

100.00  100.00  100.00 

1  Analyses  made  by  the  author. 


88  ANALYSIS  OF   MIXED  PAINTS. 

5.  Zinc-lead  white,  prepared  mostly  from  Colorado 
zinc-lead  ores,  which  also  usually  carry  copper,  silver, 
and  gold.  The  prepared  pigment  has  a  specific  gravity 
of  about  5.5,  and  consists  mainly  of  zinc  oxide  and  lead 
sulphate  in  about  equal  portions.  In  color  it  is  not  as 
white  as  pure  zinc  oxide.  In  some  cases,  at  least,  arsenic 
compounds  are  present  in  considerable  amounts.  Samples 
examined  by  the  author  had  the  following  compositions. 


I. 

II. 

III. 

IV. 

Moisture     .    .    . 

0.29 

0.58 

0.20 

0.26 

Sulphur  dioxide 

0.01 

0.01 

0.01 

0.01 

1Arsenious  oxide 

0.68 

0.47 

0.32 

1.60 

1  Antimony  oxide 

0.20 

0.33 

0.20 

0.88 

Silica  

0.14 

0.05 

0.04 

Zinc  sulphate    . 

0.78 

0.55 

1.61 

0.84 

Lead  sulphate  . 

46.00 

48.80 

46.66 

49.82 

Zinc  oxide     .    . 

51.70 

49.15 

50.90 

46.48 

Undetermined. 

0.20 

0.11 

0.05 

0.07 

100.00    100.00   100.00   100.00 

Sulphur  dioxide,  whether  occluded,  combined,  or  both, 
is  considered  the  most  objectionable  constituent  of  zinc 
pigments,  and  many  chemists  reject  shipments  containing 
more  than  0.06  per  cent  sulphur  dioxide.  Zinc  sulphate 
ranks  next  as  an  objectionable  constituent,  although  the 
percentage  permitted  is  considerably  higher.  Pigments 
containing  over  one  per  cent  of  zinc  sulphate  are  considered 
undesirable,  and  are  usually  rejected. 

95.  Estimation  of  arsenic  and  antimony  in  zinc-lead 
whites.2  Weigh  2  grams  of  the  sample  into  a  200  c.c. 
digestion  flask.  Add  7  grams  of  potassium  bisulphate, 
0.5  gram  of  tartaric  acid,  and  10  c.c.  of  concentrated  sul- 
phuric acid.  Digest  carefully  at  first,  but  finally  with 
the  full  power  of  a  Bunsen  burner,  until  a  clear  mass 
remains,  containing  but  little  free  sulphuric  acid.  Cool, 

1  Owing  to  the  conditions  of  production  it  is  assumed  that  the 
arsenic  and  antimony  exist  in  the  forms  represented. 

2  This  method  is  essentially  that  of  A.  H.  Low,  Chemical  Engineer, 
Vol.  5,  No.  3,  page  125. 


ANALYSIS  OF  SUBLIMED  LEAD.         89 

spreading  the  melt  around  on  the  sides  of  the  flask.  Add 
50  c.c.  of  water,  10  c.c.  of  strong  hydrochloric  acid,  and 
digest  for  about  20  minutes  without  boiling.  Cool  thor- 
oughly under  the  tap,  and  filter  off  the  separated  lead 
sulphate.  Dilute  the  filtrate  to  about  300  c.c.  with  hot 
water,  maintain  the  liquid  warm,  and  pass  in  hydrogen 
sulphide  for  about  15  minutes  or  until  precipitation  is 
complete.  Filter,  washing  with  hydrogen  sulphide  water. 
Digest  filter  and  contents  in  a  rather  small  amount  of 
yellow  ammonium  sulphide.  Filter  on  suction  cone, 
washing  with  as  small  a  quantity  of  water  as  possible. 

96.  Digest  the  filtrate  with  3  grams  of  potassium  bisul- 
phate  and  10  c.c.  of  strong  sulphuric  acid,  over  a  free  flame 
until  all  of  the  free  sulphur  and  the  larger  portion  of  free 
acid  is  expelled.  Cool,  spreading  the  melt  around  on  the 
sides  of  the  flask  as  before.  Add  25  c.c.  of  water  and  10 
c.c.  of  strong  hydrochloric  acid,  and  warm  to  effect  com- 
plete solution.  Cool  under  the  tap,  add  40  c.c.  of  strong 
hydrochloric  acid,  and  pass  in  hydrogen  sulphide  until 
complete  precipitation  of  the  arsenic  takes  place,  15-30 
minutes.  The  antimony  remains  in  solution.  Filter  off 
the  precipitated  arsenious  sulphide  on  to  a  weighed  Gooch 
crucible,  washing  with  a  mixture  of  two  volumes  of  hydro- 
chloric acid  and  one  of  water.  The  filtrate  is  reserved  at 
this  point  for  the  estimation  of  antimony.  The  precipi- 
tate is  next  washed  with  alcohol,  the  crucible  and  contents 
placed  in  a  small  beaker,  the  crucible  nearly  filled  with 
carbon  bisulphide,  and  the  contents  allowed  to  digest  at 
ordinary  temperature  for  about  20  minutes  in  order  to 
dissolve  the  free  sulphur.  The  carbon  bisulphide  is 
removed  by  suction,  the  crucible  dried  in  the  steam  oven, 
cooled,  and  the  precipitate  weighed  as  arsenious  sulphide 
and  calculated  to  arsenious  oxide. 

Wt.  arsenious  sulphide  X  0.8043  =  wt.  arsenious  oxide. 


90  ANALYSIS  OF  MIXED   PAINTS. 

97.  Instead  of  weighing  as  the  sulphide,  the  arsenic 
may  be  estimated  volumetrically  as  follows :  Wash  out  the 
hydrochloric    acid    from    the    sulphide    precipitate  with 
hydrogen  sulphide  water.     Digest  filter  and  contents  in  a 
little  warm  ammonium  sulphide,  filter  on  a  suction  cone, 
washing  with  a  little  dilute  ammonium  sulphide  solution. 
Place  the  filtrate  in  digestion  flask,  add  2  to  3  grams  of 
potassium  bisulphate  and  5  c.c.  of  strong  sulphuric  acid. 
Evaporate,  boiling  to  a  small  bulk,  and  then  manipulate 
the  flask  over  a  free  flame  until  the  sulphur  is  entirely 
expelled  and  most  of  the  free  acid  also.    Take  up,  after 
cooling,  by  warming  with  50  c.c.  of  water,  and  then  boil 
sufficiently  to  expel  any  possible  sulphur  dioxide.     Now 
drop  in  a  bit  of  litmus  paper  as  an  indicator,  and  then 
add  ammonia  until  the  solution  is  slightly  alkaline.     Again 
slightly  acidify  with  hydrochloric  acid  and  cool  to  room 
temperature.     Finally,  add  3  to  4  grams  of  sodium  acid 
carbonate  and  a  little  starch,  liquor  and  titrate  with  stan- 
dard iodine  solution.     Pay  no  attention  to  a  slight  discol- 
oration toward  the  end,  but  proceed  slowly  until  a  single 
drop  of  the  iodine  produces  a  strong  permanent  blue  color. 

The  iodine  solution  may  be  prepared  by  dissolving 
about  11  grams  of  iodine  in  a  little  water  with  the  addi- 
tion of  about  20  grams  of  potassium  iodide  and  diluting 
to  1  litre.  Standardize  with  arsenious  oxide.  Dissolve 
about  0.150  gram  in  5  c.c.  of  strong  hydrochloric  acid  by 
warming  very  gently,  dilute  and  neutralize  as  described 
above,  and  finally  titrate  with  the  iodine  solution.  One 
c.c.  of  the  latter  will  equal  about  0.003  gram  of  arsenic.  . 

98.  Antimony.     Very    nearly    neutralize    the    filtrate, 
reserved   for  the  antimony  estimation  with  hydrochloric 
acid,  dilute  with  double  its  volume  of  hot  water,  and  pass 
in  hydrogen  sulphide  until  all  of  the  antimony  is  precipi- 
tated.    Filter    washing    with    hydrogen    sulphide    water. 


ANALYSIS  OF  SUBLIMED   LEAD.  91 

Digest  filter  and  contents  in  a  little  ammonium  sulphide, 
filter  on  suction  cone  and  wash  with  dilute  ammonium 
sulphide.  Place  the  filtrate  in  the  digestion  flask  and 
add  about  3  to  4  grams  of  (pure)  potassium  bisulphate 
and  10  c.c.  of  strong  sulphuric  acid.  Boil  as  previously 
described  to  expel,  first  the  water,  then  all  the  free  sulphur, 
and  finally  most  of  the  free  acid.  Cool,  add  50  c.c.  of 
water  and  10  c.c.  of  strong  hydrochloric  acid.  Heat  to 
effect  solution,  and  then  boil  for  a  few  minutes  to  expel 
any  possible  sulphur  dioxide.  Finally,  add  10  c.c.  more 
of  strong  hydrochloric  acid,  cool  under  the  tap,  dilute  to 
about  200  c.c.  with  cold  water  and  titrate  with  a  standard 
solution  of  potassium  permanganate.  The  solution  ordi- 
narily used  for  iron  titrations  will  answer.  The  oxalic 
acid  value  of  the  permanganate  multiplied  by  0.9532  will 
give  the  antimony  value. 


CHAPTER  VII. 

ANALYSIS   OF    ZINC    SULPHIDE    WHITES    AND    INERT 
PIGMENTS. 

Analysis  of  Liihopone,  Ponolith,  Etc. 

99.  Moisture.     Heat  2  grams  at  105°  C.  for  3  hours. 
Loss  in  weight  represents  hygroscopic  moisture. 

100.  Barium  sulphate.   To  1  gram  add  10  cc.  of  hydro- 
chloric acid  and  10  c.c.  of  water,  heat  gently  until  excess 
of  acid  has  been  expelled,  dilute  with  100  c.c.  of  water, 
and  boil  gently  for  10  minutes.     Filter,  ignite  and  weigh 
residue  as  barium  sulphate. 

10 1.  Total  zinc.  Neutralize  the  filtrate  from  the  barium 
sulphate  with  ammonia,  make  distinctly  acid  with  hydro- 
chloric acid,  heat  to  about  80°  C.  and  titrate  with  standard 
potassium  ferrocyanide    as   described   under   Analysis   of 
White  Paints. 

102.  Zinc  sulphide.     Fuse  1  gram  in  a  large  crucible 
with  a  mixture  of  potassium  nitrate  and  potassium  chlorate 
for  about  half  an  hour.     Dissolve  the  fused  mass  in  dilute 
hydrochloric  acid,  and  boil  the  solution  with  strong  nitric 
acid  for  half  an  hour.     Filter  off  the  insoluble  residue, 
precipitate  the  combined   sulphuric   acid   in  the   filtrate 
with  barium  chloride  in  the  usual  manner,  filter,  ignite, 
and  weigh. 

Wt.  barium  sulphate  X  0.1373  =  wt.  sulphur. 
Calculate  sulphur  to  zinc  sulphide. 

103.  Zinc  oxide.    Calculate  excess  of  zinc  over  what  is 
required  to  form  the  zinc  sulphide  to  zinc  oxide. 

104.  Calcium.     Occasionally  zinc  sulphide    whites   are 
found  on  the  market,  in  which  the  barium  sulphate  has 

92 


ANALYSIS  OF   ZINC   SULPHIDE   WHITES.  93 

been  wholly  or  partially  replaced  with  calcium  sulphate, 
in  which  case  the  calcium  is  estimated  in  the  usual  manner, 
after  the  removal  of  the  zinc  as  sulphide,  and  the  sulphuric 
acid  combined  with  the  calcium  determined  as  usual. 
The  sulphuric  acid  due  to  the  calcium  must  be  deducted 
from  the  total  sulphuric  acid  obtained  by  oxidation  before 
calculating  to  zinc  sulphide. 

If  desired,  the  total  sulphur  may  be  determined  by  treat- 
ing 1  gram  of  the  pigment  with  dilute  hydrochloric  acid, 
potassium  chlorate  in  small  quantities,  and  sufficient 
bromine  to  insure  complete  oxidation.  Soluble  combined 
sulphuric  acid  may  be  determined  by  pouring  boiling  dilute 
hydrochloric  acid  on  a  weighed  portion  of  the  pigment, 
filtering,  and  precipitating  with  barium  chloride  as  usual. 
105.  ANALYSES  OF  ZINC  SULPHIDE  WHITES  BY  AUTHOR. 

I.  II. 

Lithopone.     Ponolith. 

Moisture 0.20  0.18 

Barium  sulphate 69.62  69.19 

Zinc  sulphide 28 . 05  28 . 07 

Zinc  oxide 1.55  2.27 

Undetermined 0.58  0.29 

100.00  100.00 

Analysis  of  White  Mineral  Primer,  White  Ochre,  Magne- 
site,  Whiting,  Paris  White,  English  Cliff  stone,  Etc. 

1 06.  Moisture.     Heat  2  grams  at  105°  C.  for  two  hours, 
cool  and  weigh. 

107.  Silica.    Weigh  one-half  gram  into  a  suitable  sized 
casserole.     Cover,  add  5  c.c.  of  hydrochloric  acid  (sp.  gr. 
1.1)   by  means  of  a  pipette,  without  raising  the  cover. 
After  the  effervescence  has  ceased,  rinse  off  the  beaker 
cover  with  a  little  hot  water.    Evaporate  to  dryness  and 
cool.    Add  2  c.c.  of  concentrated  hydrochloric  acid,  again 
evaporate,  and  heat  gently  for  a  few  minutes.     Cool,  and 
dissolve  up  in  100  c.c.  of  hot  water  and  10  c.c.  of  strong 


94  ANALYSIS  OF   MIXED   PAINTS. 

hydrochloric  acid,  filter,  wash,  ignite,  and  weigh.  If  1 
per  cent  or  under,  it  may  be  regarded  as  silica.  If  more,  it 
should  be  fused  with  sodium  carbonate,  dissolved  up  in 
water  and  hydrochloric  acid,  in  the  same  casserole,  and 
evaporated  to  dryness.  Heat  gently.  Add  a  little  more 
hydrochloric  acid  and  dehydrate  again.  Finally,  take 
up  in  water  acidulated  with  hydrochloric  acid,  filter, 
ignite  and  weigh  as  silica.  The  filtrate  from  the  silica 
fusion  is  treated  as  described  under  111. 

1 08.  Alumina  and  iron.     The  filtrate  from  the  original 
residue    is    made    just    perceptibly   alkaline   with  dilute 
ammonia,  the  iron  and  alumina  filtered  off,  ignited  and 
weighed  in  the  usual  manner. 

109.  Calcium.    The  filtrate  from  the  iron  and  alumina  is 
made  acid  with  acetic  acid,  boiled,  and  40  c.c.  to  50  c.c.  of 
ammonium  oxalate  solution  added.     Continue  boiling  for 
5  minutes,  filter,  and  wash  thoroughly.     Return  filter  and 
precipitate  to  same  beaker.     Add  200  c.c.  of  boiling  water 
and  25  c.c.  of  dilute  sulphuric  acid  and  titrate  with  stan- 
dard tenth-normal  potassium  permanganate. 

1  c.c.  tenth-normal  permanganate  =  0.0028g.  CaO 

1  c.c.  tenth-normal  permanganate  =  0.0050  g.  CaCo3 

1  c.c.  tenth-normal  permanganate  -  0.0086  g.CaSO4.2H3O 

1  c.c.  tenth-normal  permanganate  =  0.0068  g.  CaSO4 

1  c.c.  tenth-normal  oxalic  acid  =  0.0028  CaO 

Cryst.  oxalic  acid  X  0.444  =  CaO 

EXAMPLE :Wt.  sample  taken  =  0.250  g. 

Titration  with  permanganate  =  50.5  c.c. 

25  c.c.  standard  iron  solution  =  31.8  c.c.  perman- 

ganate 

1  c.c.  standard  iron  solution  =  .007  g.  iron,  or   .01  g. 

Fe2  O,. 

1  c.c.  tenth-normal  iron  solution  =  .0056  g.  iron 

25  c.c.  standard  iron  solution  =  31.25  c.c.      tenth 

normal  perman- 
ganate. 

1  c.c.  permanganate  solution  used  =  0.983    c.c.    tenth- 

normal  perman- 
ganate. 

50.5  c.c.  X  0.983  =  4964  c.c. 

(49.64  c.c.  X  0.0050)  -s-  0.250  =  99.28  %  CaCoO3. 


ANALYSIS  OF   ZINC   SULPHIDE  WHITES.  95 

no.  Magnesium.  The  filtrate  from  the  calcium  oxalate 
is  cooled  and  treated  with  hydrogen  sodium  phosphate, 
allowed  to  stand  for  one-half 'hour,  25  c.c.  of  strong  ammonia 
added,  allowed  to  stand  one  hour,  filtered  on  a  Gooch 
crucible,  ignited  and  weighed. 

Wt.  precipitate  X  0.7575  =  wt.  magnesium  carbonate. 

in.  Calcium  and  magnesium  oxides.  The  filtrate  from 
the  silica  fusion  should  be  treated  separately  from  the 
main  filtrate,  as  the  calcium  and  magnesium  obtained 
from  it  are  to  be  reported  as  oxides  and  not  as  carbonates. 
Precipitate  the  iron  and  alumina,  calcium  and  magnesium 
as  described  under  108,  109,  and  110. 

ii2.  Note.  If  the  sample  contains  considerable  mag- 
nesium carbonate,  the  following  modification  should  be 
observed.  After  filtering  off  the  iron  and  aluminium 
hydroxides,  they  are  redissolved  in  another  beaker, 
diluted,  and  again  precipitated  and  filtered  into  the  main 
filtrate.  The  same  treatment  is  given  to  the  calcium 
oxalate.  Magnesium  compounds  when  present  in  con- 
siderable percentages  badly  contaminate  the  other  precipi- 
tates. 

113.  ANALYSES   OF    CALCIUM  AND  MAGNESIUM    CARBON- 
ATE   PIGMENTS   BY  AUTHOR. 

I.  II.                 III.  IV. 

White  Whiting.  English  Magne- 

Ochre.  Cliffstone.  site. 

Moisture 0.11  0.30             1.60  0.07 

Silica 1.21  0.90             2.02  2.04 

Iron  oxide  and  alumina  .            .63  0 . 20             1 . 00  3.01 

Calcium  carbonate   ...       97.39  96.55  92.81  10.84 

Magnesium  carbonate    .           0 . 56  1 . 84             2 . 52  83 . 91 

Undetermined    .    .                     0.10  0.21             0.05  0.13 


100.00         100.00         100.00         100.00 


1 14.  Analysis  of  Agalite,  Terra  Alba,  Etc.  These  pig- 
ments have  essentially  the  same  composition  —  calcium 
sulphate  plus  2  molecules  of  water.  The  same  method  of 


96  ANALYSIS  OF  MIXED  PAINTS. 

analysis  may  be  pursued  as  described  under  the  analysis 
of  calcium  carbonate  pigments.  In  addition,  it  is  neces- 
sary to  determine  the  combined  water  by  ignition  to  con- 
stant weight,  and  also  to  determine  the  combined  sulphuric 
acid,  which  may  be  done  as  follows: 

Boil  0.5  gram  of  the  pigment  in  30  c.c.  of  strong  hydro- 
chloric acid  for  10  minutes  in  a  covered  beaker.  Dilute 
with  250  c.c.  of  boiling  water,  boil  5  minutes,  filter,  make 
filtrate  neutral  with  ammonia,  then  distinctly  acid  with 
hydrochloric  acid,  and  bring  to  boiling.  Add  25  c.c.  of 
barium  chloride,  boil  10  minutes,  filter,  wash  with  hot 
water,  ignite  and  weigh. 

Wt.  barium  sulphate  X  0.3433  =  combined  sulphuric 
acid. 

115.  ANALYSES   OF    CALCIUM   SULPHATE    PIGMENTS   BY 

AUTHOR. 

I.  II. 

Agalite.  Terra  Alba. 

Moisture  and  combined  water    ...         19.02  20.67 

Iron  oxide  and  alumina 0 . 29  0 . 67 

Silica 5.60  0.70 

Calcium  sulphate 74.90  76.52 

Magnesium  sulphate ...  1 . 36 

Undetermined 0.19  .08 


100.00  100.00 

Analysis  of  Silicas,  Clays,  and  other  Insoluble  Silicates. 

116.  The  silicas  used  in  the  manufacture  of  paints  and 
especially  in  wood  fillers  are  obtained  either  by  pulverizing 
quartz,  which  is  practically  pure  silica,  or  from  natural 
deposits  where  it  occurs  in  a  finely  divided  form  usually 
containing  other  minerals. 

China  clay  is  a  natural  product,  being  essentially  a 
hydrated  silicate  of  alumina.  Its  composition  varies 
according  to  the  locality  from  which  it  is  obtained. 

117.  Fusion  with  sodium  carbonate.    One-half  gram  is 


ANALYSIS   OF  ZINC  SULPHIDE   WHITES  97 

thoroughly  mixed  with  10  grams  sodium  carbonate  and 
one-half  gram  potassium  nitrate  placed  in  a  covered  plati- 
num crucible  and  fused  until  quite  clear  and  quiet.  Cool, 
and  dissolve  in  water  in  a  casserole,  provided  with  beaker 
cover,  on  the  hot  plate.  Make  acid  with  hydrochloric 
acid,  adding  the  acid  with  a  pipette,  keeping  the  casserole 
covered  to  avoid  loss.  Also  rinse  out  the  crucible  with  a 
little  acid.  After  the  effervescence  is  over,  wash  off  the 
watch  glass,  and  evaporate  to  dryness  on  the  sand  bath. 
Cool,  moisten  residue  with  hydrochloric  acid  and  evaporate 
to  complete  dryness  again.  Dissolve  in  10  c.c.  of  hot  water 
and  10  c.c.  of  hydrochloric  acid.  Filter,  ignite  and  weigh 
precipitate  as  silica. 

If  barytes  is  suspected  to  be  present,  the  sodium  carbo- 
nate fusion  is  dissolved  in  hot  water  and  the  barium  car- 
bonate filtered  off,  dissolved  in  hydrochloric  acid,  and 
precipitated  with  a  few  drops  of  sulphuric  acid  in  the  usual 
manner.  The  filtrate  from  the  barium  sulphate  is  added 
cautiously  to  the  filtrate  from  the  barium  carbonate,  the 
mixed  filtrate  made  acid  and  the  silica  dehydrated  as 
described  above. 

118.  The  filtrate  from  the  silica  is  made  slightly  alkaline 
with  ammonia,  and  the  iron  and  alumina  precipitated, 
washed,  redissolved,  reprecipitated  to  free  from  sodium 
salts,  filtered,  ignited  and  weighed  in  the  usual  manner. 

The  filtrate  from  the  iron  and  alumina  is  treated  with 
ammonium  oxalate,  and  after  being  allowed  to  stand  in  a 
warm  place  the  calcium  is  filtered  off,  ignited  and  weighed 
as  calcium  oxide.  If  desired  the  calcium  may  be  estimated 
volumetrically,  as  described  under  the  analysis  of  white 
mineral  primers,  etc. 

The  filtrate  from  the  calcium  is  tested  for  magnesium 
with  sodium  hydrogen  phosphate  and  if  found,  estimated 
in  the  usual  manner. 


98  ANALYSIS  OF   MIXED   PAINTS. 

The  carbon  dioxide  is  determined  in  a  separate  portion 
of  the  sample.  The  amount  found  is  combined  with  the 
requisite  amount  of  calcium  to  form  calcium  carbonate. 
Any  excess  of  calcium  is  reported  as  the  oxide,  it  being  in 
combination  with  the  silica.  The  magnesium  is  usually 
calculated  as  magnesium  oxide  unless  the  carbon  dioxide 
is  in  excess  of  the  calcium  present,  in  which  case  it  is  cal- 
culated to  magnesium  carbonate  and  the  remainder  of  the 
magnesium  to  the  oxide. 

119.  Moisture.    Heat  2  grams  at  105°  C.  for  3  hours, 
cool  and  weigh. 

120.  Combined  water.    Weigh  2  grams  into  a  platinum 
crucible,  heat  in  the  muffle  or  over  a  strong  Bunsen  flame 
for  1  hour.     Loss  in  weight  equals  combined  water  unless 
an  appreciable  amount  of  carbonate  is  present. 

121.  Determination   of   the   alkali   metals,   sodium   and 
potassium.     Heat  gently  1  gram  of  the  sample  intimately 
mixed  with  1  part  ammonium  chloride  to  8  parts  of  pure 
calcium  carbonate.    The  alkalies  as  well  as  some  of  the 
calcium  are  converted  into  chlorides.    Cool,  treat  with 
water.    The  alkali  chlorides  will  dissolve,  while  most  of 
the  calcium  remains  undissolved.     Filter,  precipitate  the 
calcium  with  ammonia  and  ammonium  carbonate  filter, 
evaporate  to  small  bulk,  and  precipitate  any  remaining 
calcium.     Filter.     The    solution    now    contains    as    fixed 
compounds  only  sodium  and  potassium  chlorides.     Evapo- 
rate nearly  to  dryness  in  a  weighed  platinum  dish  on  water 
bath.     Cover  and  dry  completely  on  the  hot  plate,  exer- 
cising great  care  to  prevent  the  spattering  of  the  material. 
Finally  heat  gently  with  a  Bunsen  burner,  which  must  be 
held  in  the  hand  and  the  flame  waved  under  the  dish  and 
removed  as  soon  as  any  portion  of  the  dish  becomes  red 
hot.     Cool  and  weigh.     Take  up  in  water  and   add  an 
excess  of  platino-chloride  solution.     Evaporate  to  a  syrupy 


ANALYSIS  OF  ZINC  SULPHIDE   WHITES.  99 

consistency,  take  up  with  80  per  cent  alcohol,  filter  on  to 
a  weighed  Gooch  crucible,  and  wash  with  alcohol.  Dry  in 
the  steam  oven. 

Wt.  of  precipitate  X  0.1941  =  wt.  potassium  oxide. 

Calculate  to  potassium  chloride,  subtract  from  the 
weight  of  the  mixed  chlorides,  thus  obtaining  the  weight 
of  sodium  chloride  which  may  then  be  calculated  to  sodium 
oxide. 

122.  ANALYSES   OF  SILICAS   BY  AUTHOR. 

I.  II.  III. 

Moisture 0.21  0.06  0.43 

Ferric  oxide  and  alumina    .    .  0.28  0.01  1.48 

Silica 99.40  99.88  53.48 

Calcium  carbonate ...  ...  26.12 

Magnesium  carbonate      ...  ...  18.17 

Undetermined  0.11  0.05  0.32 


100.00       100.00       100.00 


ANALYSES    OF    MAGNESIUM    SILICATES    BY  AUTHOR. 

I.  II. 

Moisture 0.50  0.29 

Combined  water 2.99  3.44 

Silica 58.60  56.76 

Ferric  oxide 0.09  0.18 

Alumina 1.43  2.84 

Calcium  carbonate 2.77 

Calcium  oxide 5 . 63 

Magnesium  oxide 30 . 45  33 . 50 

Undetermined 0.31  0.22 


100.00       100.00 


ANALYSIS  OF  TOLANITE   BY  AUTHOR. 

Moisture 0.22 

Combined  water 10.42 

Ferric  oxide 0 . 09 

Alumina  sol.  in  HC1 0.39 

Silica 65.51 

Alumina „ 23.12 

Undetermined 0.25 


100.00 


100  ANALYSIS  OF  MIXED   PAINTS. 


TYPICAL  ANALYSES  OF  CLAYS.1 

I.  II.  III.           IV. 

Silica .         45.45  66.20  72.66  64.84 

Alumina 38.75  24.11  17.33  24.31 

Ferric  oxide 1.15  0.79  1.05           1.60 

Calcium  oxide 0.13          0.11 

Magnesium  oxide 0.11  ...  ...              ... 

Potassium  oxide   ......           0.17  0.96  0.36          0.24 

Sodium  oxide ...  ...  0 . 38          0 . 32 

Combined  water,  etc 13.05  7.20  8.09          8.58 

Undetermined  .'                                  1.32  0.74 


100.00       100.00       100.00       100.00 

123.  Specifications  for  paste  wood  filler.  (Bureau  of 
Supplies  and  Accounts,  Navy  Department,  1902.)  Paste 
wood  filler  shall  contain  the  following: 

Per  cent. 

Silicate 65 

Raw  linseed  oil 10 

Best  quality  rubbing  varnish 25 

The  silicate  must  be  dry,  finely  ground,  and  when  sub- 
jected to  microscopic  test  the  particles  must  show  a  needle- 
pointed  shape.  Powdered  silicate  which  shows  spherical 
fragments  will  not  be  accepted. 

The  raw  linseed  oil  must  be  absolutely  pure,  well-settled 
oil,  of  the  best  quality;  must  be  perfectly  clear,  and  not 
show  a  loss  of  over  2  per  cent  when  heated  to  212°  F.,  or 
show  any  deposit  of  foots  after  being  heated  to  that  tem- 
perature. The  specific  gravity  must  be  between  0.932  and 
0.957  at  60°  F. 

The  rubbing  varnish  to  be  of  the  very  best  quality,  and 
to  be  equal  in  quality  to  the  standards  of  rubbing  varnish, 
which  can  be  seen  on  application  to  the  general  store- 
keeper's office  at  the  various  navy  yards.  Any  indication 
of  the  use  of  rosin  or  any  other  adulterant  in  this  varnish 
will  be  sufficient  for  its  rejection. 

1  Geological  Survey  of  N.  D.,  1901. 


ANALYSIS  OF  ZINC  SULPHIDE  WHITES.  101 

The  paste  wood  filler  when  thinned  with  turpentine  to  a 
brushing  consistency  must  dry  hard  on  glass  in  24  hours. 
It  must  not  rub  up  by  friction  under  the  finger,  and  when 
immersed  in  water  must  remain  intact  for  at  least  4  hours. 
It  must  dry  full  without  lustre,  and  transparent,  so  that  it 
will  not  color  or  cloud  the  work,  and  hard  enough  to  stand 
sandpaper  without  clogging  the  paper  after  12  hours. 


CHAPTER  VIII. 

DETERMINATION  OF  FINENESS,  COVERING  POWER  AND 
TINTING   STRENGTH    OF   PIGMENTS. 

124.  Determination  of  the  comparative  fineness  of  pig- 
ments. The  comparative  fineness,  or  perhaps  better,  the 
rate  of  settling  of  pigments,  may  be  determined  by  means 
of  the  following  apparatus. 

A  is  an  ordinary  graduated  cylinder  holding  100  c.c. 

B  is  a  black  metal  shield  attached  to  the  block  D,  which 
half  surrounds  the  cylinder,  and  is  provided  with  a  round 


FIG.  6. 


opening  T3F  of  an  inch  in  diameter,  exactly  opposite  the  25 
c.c.  graduation. 

C  is  an  electric  light. 

The  cylinder  is  filled  to  the  one  hundred  c.c.  mark  with 

102 


DETERMINATION  OF  FINENESS.  103 

87°  gasoline ;  2  grams  of  the  pigment  to  be  tested  are  intro- 
duced ,  the  cylinder  stoppered,  shaken  25  times  with  a  uni- 
form motion  and  the  stop  watch  started  with  the  last  shake. 
The  cylinder  is  placed  in  position  and  the  time  noted 
until  the  outlines  of  the  aperture  can  be  plainly  observed. 
This  gives  an  excellent  method  of  determining  the  com- 
parative fineness  of  pigments  of  the  same  type. 

125.  Comparison  of  paints  for  covering  power.  The 
following  method  described  by  G.  W.  Thompson,  though 
open  to  criticism,  furnishes  in  many  cases  much  valuable 
data. 

"  Use  white  pine  boards,  30  inches  long  by  10  inches 
wide,  and,  approximately,  1  inch  thick.  Each  end  of  the 
board  is  provided  with  a  cleat  having  a  tongue  fitting  into 
a  groove  on  the  end  of  the  board  and  securely  nailed  on. 
The  entire  board,  including  the  cleats,  to  be  finished  to 
the  size  given  above.  Three  of  these  boards  may  be 
primed  with,  say,  the  following  paint  mixture : 

White  lead  paste 100  Ibs. 

Linseed  oil,  —  $  boiled 75  Ibs. 

No  attempt  is  made  to  secure  a  definite  amount  of  prim- 
ing paint  to  the  unit  of  surface;  this,  for  the  reason  that 
the  boards  may  vary  considerably  in  their  absorptive 
power.  When  this  priming  coat  is  dry,  each  board  re- 
ceives a  diagonal  stripe  of  lampblack  in  japan  about 
1  inch  wide  on  one  or  both  sides  of  the  board,  as  may  be 
desired.  When  this  black  stripe  is  dry  it  is  given  a  second 
coat  of  paint  mixed  to  a  consistency  proper  for  painting, 
the  formula  being  recorded. 

126.  "The  weight  per  gallon  of  the  paint  so  mixed  is 
then  obtained  by  finding  its  specific  gravity  and  multi- 
plying by  8.33,  which  gives  the  weight  per  gallon.  Inas- 
much as  the  board  used  has  a  total  surface  of  680  square 


104  ANALYSIS  OF  MIXED  PAINTS. 

inches,  all  that  is  required  to  do  is  to  find  what  the  ratio 
is  between  680  square  inches  and  the  spreading  rate  at 
which  it  is  desired  to  apply  the  paint  in  order  to  find  the 
fraction  of  the  gallon  to  be  applied  to  each  board.  If  the 
rate  adopted  is  1200  square  feet  to  the  gallon,  then  we 
get  the  formula: 

680  sq.  inches:  1200  sq.  feet  :  :  1  .  .    x, 

the  reciprocal  of  '  x '  being  the  fraction  of  a  gallon  of 
paint  to  be  applied  to  each  board,  one  coat.  Having  the 
weight  of  the  paint  per  gallon  we  easily  get  the  amount  of 
paint  by  weight  to  apply  to  each  board,  one  coat  on  all 
sides.  When  this  second  coat  of  paint  is  thoroughly 
dry,  a  similar  coat  is  applied;  and,  when  dry,  the  boards 
can  be  compared  for  the  covering  power  of  the  paints  on 
them.  We  mention  the  painting  of  three  boards  with 
each  paint  to  be  compared.  The  purpose  of  this  is  that 
variations  in  results  are  obtained  between  boards  which 
are  apparently  painted  in  an  identical  manner.  These 
variations  are  not  great,  but  it  is  thought  best  to  eliminate 
them,  to  a  certain  extent,  by  painting  three  boards  and 
selecting  the  one  giving  medium  results  for  comparison 
with  boards  painted  with  other  paints." 

127.  Determination   of   the   tinting   strength   of   colors. 
The  determination  of  the  tinting  strength  of  color  pig- 
ments is  a  very  necessary  operation  in  the  valuation  and 
use  of  color  pigments.    The  colors  should  always  be  com- 
pared with  a  carefully  selected  standard. 

128.  Chrome  yellows,   ochres  and  greens.     Weigh  out 
.05  gram  of  color,  place  on  a  large  glass  plate,  add  12 
drops  of  bleached  linseed  oil,  and  rub  up  with  a  flat-bot- 
tomed glass  pestle  or  muller,  then  add  1  gram  of  zinc  oxide, 
kept  solely  for  this  purpose,  and  grind  with  a  circular 
motion  fifty  times,  gather  up  with  a  sharp-edged  spatula 


DETERMINATION   OF   FINENESS.  105 

and  grind  out  twice  more  in  like  manner,  giving  the  pestle 
a  uniform  pressure. 

Weigh  out  .05  gram  of  the  color  kept  as  the  standard, 
and  treat  in  exactly  the  same  manner  as  described  above. 
Transfer  the  standard  to  a  microscope  slide  and  spread 
out  evenly,  drawing  the  spatula  in  one  direction  only, 
and  that  toward  the  end  of  the  slide.  In  like  manner 
transfer  the  prepared  sample  to  the  slide,  spread  out 
evenly  as  before,  drawing  the  spatula  in  the  same  direc- 
tion as  directed  above,  and  bringing  the  edge  of  sample 
carefully  to  the  edge  of  the  standard.  Compare  the  tints 
as  shown  on  both  sides  of  the  glass. 

129.  Reds,  red  oxides,  etc.     Use  0.02  gram  of  sample  to 
one  gram  of  zinc  oxide. 

130.  Blues  and  blacks.     Use  0.01  gram  of  sample  to  2 
grams  of  zinc  oxide  with  24  drops  of  oil. 

131.  Paste  goods.     For  testing  the  strength  of  paste 
goods  a  can  containing  pure  zinc  oxide  ground  in  bleached 
linseed  oil  should  be  kept  on  hand. 

132.  Chrome  yellows,  ochres  and  greens.     Use  0.5  gram 
of  sample  to  10  grams  of  zinc  paste.     Weigh  accurately  on 
balanced  glasses  and  grind  as  described  above. 

133.  Reds,  red  oxides,  etc.     Use  0.2  gram  of  sample  to 
10  grams  of  zinc  oxide  paste. 

134.  Blues  and  blacks.     Use  0.05  gram  sample  to  10 
grams  of  zinc  oxide  paste. 


106 


ANALYSIS  OF  MIXED   PAINTS. 


135.   GRAVITY  AND  VOLUME  OF  PIGMENTS.1 


Name  of  Pigment. 


White  lead,  Dutch  Process 6.750 

Sublimed  lead       6.396 

Zinc  lead        5 . 635 

Lead  sulphate 6 . 082 

Zinc  oxide  Green  Seal      5.470 

Zinc  oxide,  selected 5 . 554 

Lithopone 4.236 

Barytes,  domestic 4.482 

Barytes,  blanc  fixe 4 . 329 

Eng.  C.  S.  Paris  white 2.705 

Precipitated  chalk        2.580 

Terra  Alba,  French 2 . 358 

Silica,  floated 2 . 596 

Silica,  ground        2 . 550 

English  china  clay 2.596 

Talc 2.749 

Chrome  yellow,  light 6.413 

Chrome  yellow,  medium      5 . 842 

Chrome  yellow,  deep 5 . 910 

Litharge,  yellow 8.663 

Litharge,  red 8.781 

Rochelle  ochre 2.802 

Red  lead,  English 8.681 

Tuscan  red,  dark  .    . 3.660 

Chrome  green,  light 5.754 

Chrome  green,  medium 5 . 239 

Prussian  blue 1 . 956 

Chinese  blue 1.903 

German  ivory  black 2.619 

Frankfort  black 2.935 

Bone  black 2.319 

Graphite 2.293 


Sp.  Gr. 


Volume 
loose  Pig- 
ment wt.  per 
gal.  in  Ibs. 


15.17 

11.18 

6.64 

9.77 

3.57 

6.36 

8.80 

16.96 

12.95 

6.85 

2.82 

6.74 

6.47 

4.40 

3.83 

6.72 

6.12 

6.57 

12.06 

32.21 

24.07 

5.61 

26.22 

12.76 

11.51 

13.05 

2.83 

3.85 

4.55 

6.17 

5.19 

8.69 


Drugs,  Oils  and  Paints,  Vol.  XXI.,  page  299. 


CHAPTER  IX. 

THE  PRACTICAL  TESTING  OUT  OF   PAINTS. 

136.  Paints  should  be  tested   out  by  the   chemist.     The 
chemical  analysis  of  a  can  of  paint  will  tell  much  regarding 
the  value  of  that  paint,  but  a  thorough  practical  testing 
out  on  a  suitable  surface  will  tell  more,  and  the  twro  in 
conjunction  should  render  the  chemist's  report  complete 
and  above  question.     Often,  however,  the  testing  out  is 
done  by  a  so-called  "  practical  man  "  who  has  little  or  no 
knowledge  of  chemistry,  and  his  report  for  that  very  reason 
is  apt  to  be  misleading  to  the  chemist.     In  order  to  secure 
the  most  desirable  results,  the  chemist  should  do  his  own 
testing  out,  and  this  involves  a  practical  painting  knowledge 
that  can  be  gained  only  by  experience  and  under  the  guid- 
ance of  an  able  master  painter. 

137.  Equipment.    The  chemist,  if  he  is  to  do  his  own 
testing  out,  should  provide  himself  with  an  ample  equip- 
ment so  that  he  may  carry  on  his  work  unhampered.     He 
should  have  mixing  cans  large  enough  to  hold  sufficient 
paint  for  the  coat  to  be  applied  and  to  allow  stirring  without 
danger  of  slopping  over  the  side.    A  number  of  flat  paddles 
of  suitable  sizes,  a  set  of  measures  and  a  strainer,  are  also 
essential   articles.    All    paint   from   the    priming   to   the 
finishing  coat  should  be  strained,  as  it  assists  in  securing 
a  more  uniform  mixture  than  can  be  obtained  by  stirring. 
This  is  especially  necessary  where  tints  are  to  be  tried 
out. 

138.  The  chemist  should  be  provided  with  a  good  set  of 
brushes.     It  is  a  serious    mistake  to  work  with  too  few 

107 


108  ANALYSIS  OF  MIXED   PAINTS. 

brushes.  For  ordinary  testing,  the  author  believes  that 
oval  brushes  should  be  used,  and  never  a  large  flat  brush 
which  simply  mops  the  paint  on  and  does  not  assist  it  in 
penetrating  into  the  fibres  of  the  wood.  An  oval  brush, 
being  necessarily  stiffer,  rubs  the  oil  and  pigment  into  the 
wood,  thoroughly  satisfying  it.  For  trimming  and  finish- 
ing the  edges,  a  good  chiselled  varnish  brush  can  be  used 
with  advantage.  Having  provided  himself  with  a  good  set 
of  brushes,  the  paint  chemist  should  take  good  care  of 
them.  New  brushes  should  never  be  placed  in  water. 
At  the  close  of  the  day's  work,  they  may  be  laid  out  full 
of  paint  on  a  board,  but  should  not  be  left  this  way  for 
more  than  twenty-four  hours.  When  through  with  the 
brushes  for  a  time,  they  should  be  laid  in  a  regular  paint 
trough,  containing  raw  oil,  or  they  may  be  suspended  in  a 
can  of  raw  oil  containing  a  little  turpentine,  to  prevent 
the  oil  from  becoming  fatty.  They  should  not  be  allowed 
to  stand  on  end,  as  it  turns  the  painting  edge  of  the  brush. 
Neither  should  brushes  be  allowed  to  remain  for  long 
intervals  in  cans  of  paint.  Brushes  should  never  be  allowed 
to  get  "  lousy  "  through  the  paint  drying  on  the  bristles. 
In  use,  the  brush  should  be  handled  in  such  a  manner  as  to 
wear  the  bristles  to  a  chisel  edge-like  point,  and  should 
never  be  jabbed  into  corners,  but  carefully  worked  in. 

139.   The  requisites  for  a  paint.    The  requisites  for  a 
high-grade  paint  are: 

a.  Covering  power, 

b.  Spreading  capacity, 

c.  Durability, 

d.  Wearing  evenly, 

e.  Failing  by  gradual  wear,  and 

/.   Leaving  a  good  surface  for  repainting. 
In  order  to  test  out  a  paint  to  determine  to  what  degree 
it  will  fulfil  the  above  requirements,  the  chemist  must 


THE  PRACTICAL  TESTING  OUT  OF  PAINTS.        109 

have  a  clear  understanding  of  the  practical  application  of 
paint  and  the  suitability  of  different  surfaces  to  receive 
paint  of  varying  consistencies. 

140.  Relation  of  the  surface  to  the  paint.     The  surface 
on  which  the  paint  is  to  be  tested  out  is  of  prime  importance, 
as  it  vitally  affects  the  oil  and  turpentine  reduction  which 
should  be  given  the  paint.     If  the  surface  is  a  dense  close- 
grained  wood,  a  much  more  liberal  turpentine  reduction 
must  be  used  than  when  the  surface  is  more  porous,  as  in 
the  case  of  soft   pine.     The  lumber  used  should   be  well 
seasoned  and  entirely  free  from  dampness ;  and  for  outside 
paints,  the  surface  should  be  exposed  to  the  direct  rays  of 
the  sun  for  at  least  a  couple  of  days  before  applying  the 
paint,  even  if  the  surface  is  apparently  free  from  moisture. 
If  the  test  is  to  be  applied  on  a  new  building,  every  pre- 
caution should  be  taken  that  the  lumber  has  dried  out 
thoroughly  after  the  plastering  has  been  done.     It  must  be 
remembered  that  there  are  eighty  to  ninety  gallons  of 
water    in    every  hundred  square  yards  of  plaster,  and  if 
the    house  is  kept  closed  during  the  time  the  plaster  is 
drying,  the  moisture   must   pass  through  the  clapboard 
siding,    over    which    the    paint  is  to  be  spread,  in  order 
to    escape.     This  operation  is  much  slower  and  takes  a 
great  deal   longer  time  for  completion,  than  most  paint 
men    believe.      This   is   especially   true   if   the   house   is 
sheathed    with    one   or   more    thicknesses   of   paper,    be- 
tween   the    boarding    and    siding.     If   the    tests   are   to 
be   placed   on   small   test-frames,  such   as  are  described 
below,  or  on  specially  constructed  test   fences,  the   con- 
ditions affecting  the  application  of  the  paint  can  be  more 
easily  controlled. 

141.  Test  structures.     A  convenient,  practical,  and  effi- 
cient method  of  conducting  exposure  tests  is  shown  in  the 
illustration  at  the  beginning  of  this  book,  which  represents 


110  ANALYSIS  OF   MIXED   PAINTS. 

the  first  of  a  series  of  tests  which  are  being  conducted  by 
the  North  Dakota  Government  Experiment  Station. 

This  structure  is  75  feet  in  length,  6  feet  6  inches  high, 
begins  15  inches  from  the  ground,  and  faces  east  and  west. 
The  posts  are  5  feet  apart  and  bedded  in  concrete.  One 
side  of  the  structure  is  plain  boarded,  the  other  side  clap- 
boarded,  the  top  capped,  and  the  ends  boxed  in  a  suitable 
manner.  Four  kinds  of  lumber  were  used  in  the  construc- 
tion, representing  four  of  the  most  common  varieties  used 
for  house  building,  and  were  securely  nailed  to  studding  set 
1  foot  and  8  inches  apart.  The  structure  was  divided 
off  into  sections  16  inches  wide  and  5  feet  in  length,  giving 
sufficient  surface  for  the  careful  brushing  out  of  the  paint ; 
each  type  of  paint  being  applied  over  the  four  kinds  of 
wood,  and  the  work  being  three  coats  in  each  case.  Twenty- 
one  mixed  paints  and  white  leads  were  applied  on  this 
fence,  representing  prevailing  types  of  combinations. 

Figure  7  represents  a  second  series  of  exposure  tests 
begun  during  the  summer  of  1907.  These  fences  are  like 
the  one  described  above,  except  that  they  are  each  100  feet 
in  length.  There  is  a  four-inch  air-space  between  the  two 
surfaces  of  each  fence;  the  numerous  crevices  between 
the  boards  permit  of  free  circulation  of  air,  and  insures 
the  prevention  of  continued  dampness  on  the  inside  of  the 
structure.  Figure  8  illustrates  the  framework  to  which 
the  boards  and  siding  were  nailed. 

142.  A  more  convenient  method  for  making  exposure 
tests,  the  painting  of  which  may  be  done  in  the  laboratory, 
is  illustrated  in  Fig.  9.  These  test  frames,  so-called, 
have  the  additional  merit  of  being  easily  transported  from 
one  place  to  another  for  inspection.  These  frames  are  3 
feet  in  length  and  16  inches  in  width,  the  edge  of  the  upper 
clapboard  projecting  half  an  inch  above  the  cleats,  and 
the  lower  clapboard  set  out  a  little,  so  that  two  or  more 


X 

/    V     OF  THE  \ 

I    UNIVERSITY    J 


THE  PRACTICAL  TESTING  OUT  OF  PAINTS.        Ill 

frames  may  be  put  together  forming  a  unit  surface,  exactly 
similar  to  the  side  of  a  house.  These  frames  are  made  to 
be  screwed  to  a  framework  like  that  illustrated  in  Fig.  8. 
The  clapboards,  four  in  number,  are  set  four  inches  to  the 


FIG   9.    PORTABLE  TEST  FRAMES. 


weather,  and  are  of  two  kinds  of  wood.  The  arrangement 
of  the  back  cleats  a,  a,  a  and  the  end  strips  b,  b  through 
which  the  screws  are  inserted  to  hold  the  frame  to  the 
skeleton  fence,  are  clearly  shown  in  the  illustrations. 

These  end  strips  serve  a  much  more  important  pur- 
pose, and  one  which  makes  the  tests  much  more  valuable 
than  on  a  plain  board  surface,  in  that  it  tests  out  the 
brushing  qualities  of  the  paint  very  thoroughly.  A  poor 
paint  will  often  brush  out  satisfactorily  on  an  ordinary 
flat  section  of  board,  but  will  at  once  show  its  inferior 
quality  when  the  painter  attempts  to  work  it  into  the 


112  ANALYSIS  OF  MIXED   PAINTS. 

corners  and  brush  it  away  from  the  end  strips,  on  the  clap- 
board surface.  In  fact,  it  closely  reproduces  the  actual 
conditions  which  the  painter  would  encounter  in  applying 
the  paint  on  an  average  house. 

143.  Application  of  the  priming  coat.     In  order  to  secure 
the  best  results  with  any  given  paint,  three  coats  should  be 
applied;  of  these  three  the  most  important  is  the  priming 
coat.     It  compares  with  the  foundation  of  a  house,  which, 
if  not  solidly  and  firmly  constructed,  renders  the  whole 
superstructure  unstable.    The  priming  coat,  if  not  bedded 
thoroughly  in  the  wood,  will  not  serve  to  anchor  and  firmly 
bind  the  two  additional  coats  to  the  surface.    The  essential 
consideration  with  the  priming  or  first  coat  is  to  secure 
suitable  penetration  into  the  wood.     In  other  words,  the 
wood  must  be  thoroughly  satisfied.    The  necessity  of  this 
is  explained  with  great  force  and  clearness  by  J.  B.  Camp- 
bell, in  his  work  entitled  "  Practical  Painting." 

144.  The  paint  to  be  tested  out  if  of  the  ready  mixed 
type  should  be  thoroughly  "  broken  up,"  first  pouring  off 
the  oil  portion,  stirring  the  residue  until  free  from  lumps, 
and  then  gradually  working  the  oil  portion  back  into  the 
paste.    This  is  best  accomplished  by  removing  the  entire 
contents  of  the  can  into  a  larger  mixing  can,  kept  solely 
for  this  purpose.    The  consistency  of  the  paint  after  being 
"  broken  up  "  should  be  carefully  noted,  whether  it  is 
thin,  medium,  or  heavy,  as  the  amount  of  reduction  which 
the  paint  will  stand  depends  largely  on  its  consistency. 

145.  Raw  linseed  oil  should  almost  without  exception 
be  used  instead  of  boiled  oil  for  reducing  the  paint  for  the 
priming  coat.     Raw  oil  dries  slowly  and  from  the  bottom 
up,  which  allows  it  to  be  thoroughly  absorbed  and  to 
harden  uniformly.     Boiled  oil  does  not  penetrate  the  wood, 
owing  to  its  rapid  drying  qualities,  and  hence  the  coating 
formed  is  a  surface  coating  only,  and  does  not  become 


THE   PRACTICAL  TESTING  OUT  OF  PAINTS.         113 

firmly  anchored  to  the  wood.  Turpentine  should  be  used 
liberally  in  the  priming  coat,  as,  by  reducing  the  specific 
gravity  and  rendering  the  oil  more  mobile,  it  assists  it  in 
penetrating  into  the  deeper  pores  of  the  wood ;  thus  securing 
increased  penetration  and  also  more  rapid  drying.  The 
harder  and  closer  grained  the  wood,  the  larger  the  amount 
of  turpentine  required. 

146.  The  following  oil  and  turpentine  reductions l  will 
enable  the  chemist  to  judge  the  reduction  required  in  most 
cases. 

147.  Oil  reductions.     "  A  full  oil   reduction  consists  of 
oil  only,  with  the  exception  of  -£%  gallon  of  turpentine, 
to  the  gallon  of  paint,  to  assist  in  penetration;  this  is  not 
enough  turpentine  to  destroy  the  lustre  of  the  paint,  and 
will  accomplish  the  purpose  of  penetrating  a  hard  or  glossy 
surface,  where  it  would  be  unsatisfactory  to  apply  paint 
without  the  addition  of  a  small  percentage  of  this  thinner. 

148.  "A  liberal  oil  reduction  consists  of  J  oil  and  J 
turpentine  to  form  the  total  amount  of  reducers;  this  amount 
of  turpentine  will  cause  more  rapid  and  even  penetration, 
but  will  not  destroy  the  lustre  of  heavy-bodied  paint. 

149.  "A  medium  oil  reduction  consists  of  }  oil  and  £ 
turpentine  to  form  the   total  amount  of   reducers;  this 
amount  of  turpentine  will  destroy  part  of  the  lustre  and 
cause  deep  penetration  on  a  hard  surface. 

150.  "  Turpentine  reductions.    A  full  turpentine  reduc- 
tion consists  of  nothing  but  turpentine,  and  is  used  for 
producing  a  flat  paint. 

151*  "A  liberal  turpentine  reduction  consists  of  f  turpen- 
tine and  }  oil,  to  form  the  total  amount  of  reducers. 

152.  "A  medium  turpentine  reduction  is  half  turpentine 
and  half  oil. 

i53«    "Dark  shades  require  more  turpentine  to  produce 

1  Campbell,  Practical  Painting,  p.  63. 


114  ANALYSIS  OF  MIXED  PAINTS. 

the  same  results,  as  to  penetration  and  flattening  the  paint, 
than  light  shades.  Zinc  and  combination  paints  require 
more  turpentine  than  strictly  pure  lead  to  produce  the 
same  results,  as  to  destroying  the  lustre  of  the  paint. 
Where  light  shades  require  J  gallon  of  turpentine  to  pro- 
duce the  desired  results  as  to  flattening  or  destroying  the 
lustre  and  secure  penetration,  dark  shades  require  T3F  of  a 
gallon  to  produce  like  results." 

154.  It  is  also  well  to  remember  in  making  the  reduction 
that  turpentine  reduces  twice  as  fast  as  raw  oil.    The 
consistency  to  which  the   paint  should   be  reduced   for 
priming  must  necessarily  be  left  to  the  judgment  of  the 
person  applying  it,  and  hence  no  definite  directions  can  be 
given,  but  the  following  directions  given  by  Campbell 1 
have  been  found  very  helpful  by  the  author. 

155.  "  In  priming  soft  wood,  the  paint  should  be  applied 
with  a  full  brush,  and  enough  paint  used  at  all  times  to 
satisfy   the    surface.     It   should    be    well     brushed,    and 
especially  on  the  harder  grain,  to  assist  or  force  the  paint 
into  this  close  grain,  and  remove  by  hard  brushing,  any 
surplus  paint  that  remains  on  the  surface.     On  hard  or 
close  grained  wood  a  medium  full  brush  should  be  used  in 
applying  the  paint,  as  this  class  of  wood  does  .not  possess 
the  absorbing  properties  of  softer  woods,  but  requires  more 
brushing  in  order  to  force  a  sufficient  amount  of  oil  and 
binder  into  the  wood  and  at  the  same  time  not  leave  an 
excess  of  paint  on  the  surface. 

156.  "  If  the  priming  coat  is  of  the  proper  consistency, 
carrying  sufficient  pigment  to  fill  and  hide  the  grain,  and 
well  brushed  into  the  wood,  most  of  the  absorption  will 
have  ceased  with  this  coat  and  no  excess  of  pigment  left 
on  the  surface.    This  thin  coat  will  allow  the  second  coat 
to  penetrate  through   and  satisfy  any  part  of  the  wood 

1  Practical  Painting,  p.  68. 


THE  PRACTICAL  TESTING  OUT   OF   PAINTS.       115 

which  was  not  fully  filled  at  the  time  of  priming,  and  also 
allow  the  second  coat  to  bind  itself  to  the  wood  and 
priming  coat." 

157.  Application  of  the  middle  coat.     The  priming  coat 
should  be  given  ample  time  to  dry  before  applying  the 
second  coat,  which,  as  Mr.  Campbell  states  with  much  truth, 
should  be  "  considered  the  medium  between  the  foundation 
coat  and  the  protecting  or  finishing  coat."     Careful  judg- 
ment should  be  exercised  in  preparing  the  paint  for  this 
coating.     "  It  must  not  be  too  elastic,  and  should  dry  firm 
without  a  high  gloss.    Too  heavy  an  oil  reduction  will 
leave  a  high,  glossy  surface,  over  which  the  finishing  coat 
will  not  adhere  or  properly  dry."      Sufficient  turpentine 
should  be  used  to  secure  the  necessary  penetration  into  the 
priming  coat  and  to  "  flatten  "  out  the  paint  so  that  it 
will  show  little  or  no  gloss  after  48  to  72  hours.     Over  such 
a  surface,  the  finishing  coat  can  be  applied  evenly,  smoothly, 
and  with  great  adherence.    The  directions  for  application 
as  issued  by  most  paint  manufacturers  are  apt  to  fall  short 
in  the  amount  of  turpentine  necessary  for  the  proper  appli- 
cation of  the  second  coat. 

158.  Nail  holes  and  cracks  should  be  carefully  puttied. 
Cheap  putty  should  be  avoided,  as  it  is  apt  to  turn  yellow 
and  ultimately  crumble  and  fall  out.     It  is  often  better  for 
the  paint  chemist  to  make  his  own  putty,  using  medium 
whiting,  raw  oil  and  paste  white  lead  to  about  20  per  cent  of 
the  whiting  used.    The  mixture  should  be  carefully  kneaded 
and  worked  until  of  stiff  consistency. 

159.  If  the  work  is  to  be  only  two-coat,  the  paint  should 
have  a  full  oil  reduction,  so  as  to  insure  sufficient  elasticity 
and  opacity,  and  should  be  worked  out  well  under  the  brush. 

1 60.  Application  of    third   coat.    The   paint  for    this 
coat  should  be  of  good  consistency,  with  a  full  raw  oil 
reduction,  so  that  it  may  be  brushed  out  smoothly  and 


116  ANALYSIS  OF  MIXED  PAINTS. 

evenly,  and  be  sufficiently  elastic  so  as  to  withstand  severe 
exposures.  Too  much  importance  cannot  be  placed  on  the 
thorough  brushing  of  the  paint,  as  the  durability  and  pro- 
tection it  affords  are  dependent  to  a  great  extent  upon  the 
thoroughness  with  which  this  is  done.  Paint  flowed  on 
will  soon  crack  and  come  off,  while,  if  plenty  of  muscle  is 
used,  it  will  make  the  finishing  coat  adhere  more  firmly  to 
the  second  coat. 

161.  Application  of  paste  leads  and  paste  paints.  In 
testing  out  paste  paints  and  leads  some  convenient  method 
should  be  adopted  for  calculating  the  amount  of  oil  used 
in  gallons  per  hundred  pounds  of  paste.  One  of  the 
simplest  schemes  is  to  weigh  out  the  leads  or  pastes  in 
12 J  oz.  quantities  or  multiples  thereof.  Then  each  ounce 
of  oil  used  is  equivalent  to  one  gallon  per  hundred  pounds 
of  paste. 

One  gallon  is  equivalent  to  128  oz. 

One  hundred  pounds  are  equivalent  to  1600  oz. 

1600  -  128  =  12.5 

In  this  way  the  necessary  quantities  of  turpentine  and 
drier  can  be  rapidly  calculated  and  measured  out.  For 
instance,  if  a  specification  to  be  tested  out  read, 

100  Ibs.  white  lead 
7  gal.  raw  linseed  oil 
J  gal.  turpentine 
J  gal.  turpentine  drier, 

the  above  scheme  would  call  for 

12  J  oz.  white  lead 
7  oz.  raw  linseed  oil 
J  oz.  turpentine 
J  oz.  turpentine  drier. 


THE  PRACTICAL  TESTING  OUT  OF  PAINTS.         117 

If  larger  amounts  were  required,  the  necessary  multiple 
of  12J  should  be  used  and  the  other  figures  increased 
accordingly. 

162.  Driers.    The  proper  use  of  driers  is  often  a  per- 
plexing problem  with  the  paint  chemist.     Campbell l  says : 
"  A  wide  experience  with  the  products  as  used  by  the 
painter   shows  the   greatest   possible   difference   between 
them.     Some  of  them  are  sufficiently  powerful  so  that  even 
5  per  cent  added  to  raw  oil  is  enough  to  cause  it  to  dry  as 
fast  as  with  boiled  oil,  and  not  only  that,  but  to  dry  through- 
out or  from  the  bottom  up,  and  not  merely  surface  dry, 
as  will  boiled  oil.     Others  again  are  so  loaded  with  rosin 
and  petroleum  products  and  so  deficient  in  true  drying 
properties  that  25  per  cent  or  more  is  required  to  accom- 
plish this  result,  and  then  the  resulting  surface  will  be 
spongy  or  brittle,  as  the  case  may  be,  but  in  any  event 
lacking  in  durability."     In  the  face  of  these  conditions  the 
only  recourse  left  the  chemist,  is  to  test  out  his  driers 
thoroughly  as  described  in  a  later  chapter. 

163.  "  The  Japan  or  drier  should  be  mixed  with  the 
paint  while  it  is  in  semi-paste  form.    The  mixing  is  thus 
uniform  and  the  results  satisfactory.    If  an  attempt  is 
made  to  add  it  after  the  paint  is  ready  for  the  brush,  the 
Japan  is  liable  to  curdle;  it  will  be  difficult  to  mix  uni- 
formly and  the  resulting  work  liable  to  be  spotted,  drying 
flat  in  some  places  and  glossy  in  others."    It  should  be 
borne  in  mind  that  paints  containing  zinc  or  dark  colors  will 
require  more  Japan  than  white  lead  alone,  provided  that  it 
is  essential  to  dry  in  a  given  time. 

1  Practical  Painting,  p.  66. 


118 


ANALYSIS   OF  MIXED   PAINTS. 


CHAPTER  X. 

ANALYSIS    OF    WHITE    PAINTS. 

164.  Qualitative  analysis  of  white  paints.     Carbonates. 

Effervescence  with  concentrated  hydrochloric  acid  indi- 
cates carbonates,  or  hydrogen  sulphide  if  zinc  sulphide  be 
present. 

Barytes,  silica,  day,  or  other  silicates.  Boil  above  mix- 
ture 5  minutes,  dilute  with  boiling  water,  filter.  An 
insoluble  residue  may  be  barytes,  silica,  clay  or  other 
silicates.  Test  for  barytes  with  flame  test,  using  a  plati- 
num wire. 

Sulphates.  Test  a  small  portion  of  the  acid  filtrate  for 
combined  sulphuric  acid  with  a  few  drops  of  barium  chlo- 
ride. 

165.  Lead.    Test  another  small  portion  of  the  acid  fil- 
trate with  sulphuric  acid.    A  white  precipitate  indicates 
lead. 

Zinc.  Take  another  small  portion  of  the  acid  filtrate 
and  add  a  few  drops  of  potassium  ferrocyanide.  A  white 
precipitate  with  a  bluish  tinge  indicates  zinc. 

Calcium.  The  remaining  portion  of  the  acid  filtrate  is 
made  alkaline  with  ammonia  and  saturated  with  hydro- 
gen sulphide  for  5  minutes.  Filter  and  test  filtrate  for 
calcium,  with  ammonium  oxalate,  setting  aside  in  a  warm 
place. 

Magnesium.  After  completely  precipitating  the  cal- 
cium, add  a  few  drops  of  hydrogen  sodium  phosphate.  A 
precipitate  on  standing,  indicates  the  presence  of  magne- 
sium compounds. 

119 


120  ANALYSIS   OF  MIXED   PAINTS. 

Quantitative  Analysis  of  White  Paints. 

166.  Total  lead.     Weigh  1  gram  of  the  dry  pigment  into 
a  250  c.c.  beaker.    Add  30  c.c.  of  strong  hydrochloric  acid, 
boil  5  minutes,  add  50  c.c.  of  hot  water,  heat  15  minutes 
longer,  settle,  filter  while  hot,  and  wash  thoroughly  with 
boiling  water.     Casein  and  other  products  of  a  similar 
nature  are  occasionally  used  in  the  manufacture  of  mixed 
paints  in  considerable  quantities,  and  the  analyst  should 
always  be  on  the  lookout  for  the  possible  presence  of  these 
substances. 

The  solution  is  made  just  alkaline  with  ammonia,  then 
just  acid  to  litmus  with  hydrochloric  acid;  dilute  to  about 
350  c.c.  Cool,  pass  in  hydrogen  sulphide  gas,  noting  the 
color  of  the  precipitate ;  if  gray,  some  zinc  is  being  thrown 
down ;  if  reddish  black,  the  solution  is  too  acid ;  add  a  few 
drops  of  dilute  acid  or  ammonia  as  the  case  requires. 
Settle,  filter,  and  wash  with  cold  water.  Digest,  filter  and 
precipitate  in  warm,  dilute  nitric  acid,  until  the  lead  is 
completely  dissolved.  Filter  on  suction  funnel,  wash  with 
boiling  water,  add  5  c.c.  of  dilute  sulphuric  acid  to  filtrate, 
and  evaporate  until  sulphur  trioxide  fumes  appear.  Cool, 
add  25  c.c.  of  water,  25  c.c.  of  alcohol;  allow  to  stand  one- 
half  hour  with  occasional  stirring;  filter,  using  Gooch 
crucible,  wash  with  dilute  alcohol,  dry,  heat  gently  over 
ordinary  lamp,  and  weigh  as  lead  sulphate. 

167.  Calcium.    The  filtrate  containing  the  zinc,  calcium 
and  possibly  magnesium  is  made  slightly  alkaline  with 
ammonia,  heated   to  the  boiling-point  and  a  stream  of 
hydrogen  sulphide  gas  passed  into  the  solution  for  about 
10  minutes.    Add  5  grams  ammonium  chloride,   boil  10 
minutes.   This  treatment  renders  the  precipitate  less  slimy. 
Settle,  decant,  filter,  and  wash.     Reject  precipitate. 

Evaporate  the  filtrate  from  above  precipitate  to  about 


ANALYSIS    OF    WHITE    PAINTS.  121 

150  c.c.,  make  alkaline  with  ammonia,  add  ammonium 
oxalate  (50  c.c.  for  1  gram  of  lime),  usually  20  c.c.  is  suffi- 
cient, and  set  in  a  warm  place  for  2  or  3  hours.  Filter, 
wash,  ignite,  and  weigh  as  calcium  oxide,  or  titrate  precipi- 
tate with  permanganate,  as  described  under  analysis  of  the 
calcium  carbonate  pigments.  Barium  carbonate  is  still  to 
be  found  in  certain  mixed  paints,  and  it  is  advisable  to 
test  for  the  presence  of  soluble  barium  before  precipitating 
the  calcium. 

1 68.  Magnesium.     The  filtrate  from  the  calcium  oxalate 
should  be  tested  for  magnesium,  and  if  found,  estimated  in 
the  usual  manner. 

169.  Zinc  oxide.     Dissolve  1  gram  of  pigment  in  dilute 
hydrochloric  acid,  boil,  dilute  to  about  200  c.c.  and  heat 
to  about  80°  C.    Add  about  3  grams  of  solid  ammonium 
chloride,  and  titrate  with  standard  potassium  ferrocyanide, 
using  uraninum  acetate  or  nitrate  as  the  indicator.     Plac- 
ing a  drop  of  the  indicator  on  a  porcelain  plate  and  adding 
1  drop  of  solution,  the  formation  of  a  brownish  precipitate 
indicates  the  end  point.     Sufficient  time  should  be  allowed 
for  the  color  change  to  take  place.     If  the  percentage  of 
lead  is  considerable,  add  3  drops  of  sulphuric  acid  before 
titrating. 

The  ferrocyanide  solution  is  obtained  by  dissolving  43.2 
grams  in  bne  litre,  and  titrating  against  a  standard  zinc 
solution  obtained  by  dissolving  10  grams  of  pure  zinc  in 
hydrochloric  acid,  adding  50  grams  of  ammonium  chloride, 
and  making  to  one  litre.  This  method  has  been  often 
criticised  as  inaccurate,  but  if  the  titrations  of  the  sample 
and  of  the  standard  zinc  solution  are  made  under  exactly 
the  same  conditions  as  regards  acidity,  temperature,  and 
concentration,  the  author  believes  that  the  results  obtained 
will  be  entirely  satisfactory. 

170.  Lead    sulphate.      Dissolve    0.5     gram    in     water 


122  ANALYSIS  OF  MIXED   PAINTS. 

25  c.c.,  ammonia  10  c.c.,  hydrochloric  acid  in  light 
excess. 

Dilute  to  200  c.c.  and  add  a  piece  of  aluminum  foil 
which  should  about  cover  the  bottom  of  the  beaker.  It  is 
important  that  this  be  held  at  the  bottom  by  a  glass  rod. 
Boil  gently  until  the  lead  is  precipitated.  Completion  of 
this  is  shown  by  the  lead  ceasing  to  coat  or  cling  to  the 
aluminum.  Decant  through  a  filter,  pressing  the  lead 
sponge  into  a  cake  to  free  it  from  solution.  Add  to  filtrate 
a  little  sulphur-free  bromine  water,  boil  until  the  bromine 
is  excelled,  add  15  c.c.  of  barium  chloride,  boil  10  minutes, 
filter,  wash  with  hot  water,  ignite,  and  weigh  as  barium 
sulphate.  Calculate  to  lead  sulphate  by  multiplying  by 
1.3  as  a  factor,  unless  calcium  sulphate  is  present,  in  which 
case  it  is  advisable  to  make  use  of  Thompson's  separation, 
section  177. 

In  the  absence  of  barium  sulphate,  the  combined  sul- 
phuric acid  may  be  estimated  by  H.  Mannhardt's  method : 
Triturate  1  gram  of  pigment  with  1  gram  of  sodium  car- 
bonate, very  intimately  in  an  agate  mortar.  Boil  gently 
for  10  minutes  the  combined  sulphuric  acid,  and  in  the 
case  of  colors  containing  chromates,  the  chromic  acid  will 
be  almost  if  not  entirely  extracted,  and  may  then  be  esti- 
mated in  the  filtrate  in  the  usual  manner.  If  necessary 
collect  the  insoluble  portion  on  a  filter,  dry,  Jetach  and 
triturate  a  second  time. 

171.  Basic  carbonate  of  lead.  (White  lead.)  After 
deducting  the  amount  of  lead  present  in  the  pigment  as 
sulphate  of  lead,  calculate  the  rest  of  the  lead  as  white  lead 
by  multiplying  the  remaining  sulphate  by  0.852,  unless 
sublimed  lead  is  suspected  to  be  present;  in  which  case, 
estimate  the  sublimed  lead  by  the  method  described  in 
section  84,  and  then  calculate  any  remaining  lead  to  the 
basic  carbonate  of  lead. 


ANALYSIS   OF   WHITE   PAINTS.  123 

172.  The    insoluble    residue,    from    166,    may    contain 
barytes,  magnesium  silicate,  silica  and  clay.     Ignite  filter 
and  residue  until  white,  weigh  as  total  insoluble  matter; 
grind  in  agate  mortar  with  about  10  times  its  weight  of 
sodium  carbonate,  fuse  for  1  hour  in  a  platinum  crucible, 
and  dissolve  out  in  hot  water. 

173.  Barium  sulphate.     The  solution  from  the  fusion  is 
filtered.     The  residue  consists  of  barium  carbonate,  mag- 
nesium carbonate,  etc.,  and  is  washed  with  hot  water. 
The  filtrate  and  washings  are  saved.     Pierce  filter  paper 
and  wash  precipitate  into  clean  beaker,  wash  with  hot 
dilute  hydrochloric  acid,  finish  washing  with  hot  water, 
heat  to  boiling,  add  10  c.c.  of  dilute  sulphuric  acid  to  preci- 
pitate barium,  filter,  ignite,  and  weigh  as  barium  sulphate. 

174.  Silica.    The  filtrate  from  the  barium  sulphate  is 
added  with  care  to  the  filtrate  reserved  in  173,  making 
distinctly  acid;  evaporate  to  complete  dryness,  cool,  add 
15  c.c.  of  hydrochloric  acid,  and  again  evaporate  to  dryness 
and   heat   gently.      Again   dissolve  in  50  c.c.  of   water, 
acidify  with  hydrochloric  acid,  heat  to  boiling,  cool,  settle, 
filter,  ignite,  and  weigh  as  silica. 

175.  Alumina.    The  filtrate  from  the  silica  will  contain 
all  of  the  alumina  except  that  which  was  dissolved  in  166, 
with  hydrochloric  acid.     This  is  quite  constant,  varying 
from  .004  to  .005  gram  per  gram  of  clay.     The  acid  filtrates 
are  made  slightly  alkaline  with  ammonia,  and  boiled  until 
odor  of  ammonia  disappears.     Settle,  filter,  wash,  ignite, 
and  weigh  as  alumina. 

Wt.  alumina  X  2.5372  =  wt.  clay. 

Wt.  clay  X  .4667  =  wt..  of  silica  in  clay. 

Any  difference  greater  than  5  per  cent  may  be  considered 
as  free  or  added  silica,  according  to  Scott. 

176.  Calcium    and    magnesium    oxides.     If    qualitative 


124  ANALYSIS  OF  MIXED  PAINTS. 

test  shows  presence  of  magnesium  in  insoluble  residue  from 
166  it  was  present  probably  as  magnesium  silicate.  Treat 
filtrate  from  175  for  calcium  and  magnesium  in  usual 
manner,  calculating  results  to  calcium  and  magnesium 
oxides. 

Magnesium  silicate  contains  3-5  per  cent  combined 
water  and  about  60  per  cent  silica. 

177.  Mixed     carbonates    and    sulphates.     Occasionally 
paints    are    met  with  which    contain   calcium  sulphate, 
calcium  carbonate,  sulphate  of  lead  and  white  lead  (basic 
carbonate  of  lead),  in  which  case  it  is  necessary  to  make 
a  separation  of  the  calcium  compounds,  which  may  be 
effected  by  Thompson's  method  as  follows : 

To  1  gram  of  the  sample  are  added  20  c.c.  of  a  mixture 
of  9  parts  alcohol  (95  per  cent)  and  1  part  of  concentrated 
nitric  acid.  Stir,  and  allow  to  stand  20  minutes.  Decant 
on  a  filter  and  repeat  the  treatment  with  the  acid-alcohol 
mixture  4  times,  allowing  it  to  stand  each  time  before 
decanting.  The  calcium  carbonate  will  go  into  solution, 
while  the  calcium  sulphate  or  gypsum  remains  undissolve.d. 
Add  filter  and  contents  to  the  residue  remaining  in  the 
beaker;  dissolve  in  hydrochloric  acid  with  sufficient  water 
to  insure  the  solution  of  the  calcium.  Make  alkaline  with 
ammonia,  pass  in  hydrogen  sulphide  for  10  minutes,  boil, 
settle,  filter.  The  filtrate  and  washings  are  concentrated 
to  about  150  c.c.  and  the  calcium  precipitated  with  ammo- 
nium oxalate  in  the  usual  manner.  The  ignited  precipi- 
tate is  calculated  to  hydrated  calcium  sulphate. 

178.  Calculations.    The  ignited  precipitate  of  calcium 
oxide  obtained  from  the  portion  insoluble  in  the  acid  alco- 
hol mixture  is  subtracted  from  the  total  calcium  weighed 
as  oxide;  the  remaining  calcium  oxide  is  calculated  to  cal- 
cium carbonate.    The  total  carbon  dioxide  is  determined 
in  a  portion  of  the  sample,  the  portion  due  to  the  calcium 


ANALYSIS   OF  WHITE  PAINTS.  125 

carbonate  is  deducted  from  the  total  amount,  and  the 
remainder  calculated  to  basic  carbonate  of  lead.  The 
combined  sulphuric  acid  due  to  the  sulphate  of  lime  is 
deducted  from  the  total  combined  sulphuric  acid,  and  the 
remainder  calculated  to  sulphate  of  lead. 

Wt.  calcium  oxide  X  3.071 5  =  hydrated  calcium  sulphate. 

Wt.  calcium  oxide  X  1.784  =  calcium  carbonate. 

Wt.  calcium  carbonate  X  0.440  =  carbon  dioxide. 

Wt.  carbon  dioxide  X  8.8068  =  basic  carbonate  of  lead. 

Wt.  of  hydrated  sulphate  of  lime  X  0.4561  =  combined 
sulphuric  acid. 

Wt.  of  combined  sulphuric  acid  X  3. 788  =  sulphate  of  lead. 

179.  TYPICAL  ANALYSES  OF  MIXED  PAINTS.1 

I.  II.  III.                 IV. 

Color Stone.  Lead.  Gray.            White. 

Can l.OOqt.  4.06  qt.  l.OGqt.  l.OSqt. 

Contents 90  qt.  4.01  qt.  l.OSqt.  .93  qt. 

Net  weight     ...     2  Ibs.  14  oz.  16  Ibs.  3  oz.    4  Ibs.  3  Ibs.  4  oz. 

Vehicle 50.1  34.2  38.2  36.9 

Pigment     ....     49.9  65.8  61.8  63.1 

100.00     100.00     100.00     100.00 


89.6 
10.1 


Linseed  oil  ... 
Benzine  drier 
Turpentine  drier 
Water 

ANALYSIS  OF   VEHICLE. 

.     68.9            90.4              90.6 
.     16.1               ...                 3.4 
9.4                4.0 
15  0              02                20 

100.00  100.00  100.00     100.00 

ANALYSIS  OF  PIGMENT. 

White  lead  .           .21.73  49.53  16.64              21.56 

Lead  sulphate     .    .     0.85  0.44  13.48                1.09 

Zinc  oxide   ....  47.89  49.64  39.80              49.25 

Calcium  carbonate .  21 . 98  ...  10 . 68                1 . 80 

Barytes ...  18.93 

Silica 5.41 

Magnesium  silicate,        ...  ...  ...               25.87 

Color,  undeter- 
mined, etc.      .    .     2.14  0.39  0.47                0.43 


100.00         100.00  100.00  100.00 

1  Analyses  made  by  author. 


126 


ANALYSIS  OF  MIXED   PAINTS. 


1 80.  No.  1  is  a  fair  type  of  a  large  number  of  mixed 
paints,  short  in  volume,  short  in  weight,  low  in  pigment, 
nearly  one-third  of  the  vehicle  being  benzine  and  water, 
and  27  per  cent  of  total  pigment  inert  material. 

No.  2  is  a  strictly  first-class  paint  in  every  respect,  full 
measure,  16  Ibs.  to  the  gallon,  pure  turpentine  drier  and 
high  white  lead  content. 

No.  3  is  full  measure  and  full  weight.  The  percentage  of 
drier  is  well  within  the  usually  accepted  limits,  but  the 
manufacturer  obtains  a  considerable  relief  by  the  use  of 
nearly  30  per  cent  of  inert  pigments  costing  only  a  small 
fraction  of  the  price  of  white  lead  or  zinc.  This  paint  also 
has  a  very  small  percentage  of  added  water. 

No.  4  is  7  per  cent  short  in  volume,  is  low  in  lead  pig- 
ments, and  contains  nearly  28  per  cent  of  inert  pigment, 
which  in  this  case  is  mainly  magnesium  silicate. 

181.  Calculation  of  the  approximate  cost  of  mixed  paints 
using  No.  I  and  No.  II  as  types. 


COST  OF  VEHICLE. 


No. 

I. 

No. 

II. 

Liquid. 

Cost  per 
Gallon 

Gal. 

Total 
Cost. 

Gal. 

Total 

Cost. 

Linseed  oil    .... 
Turpentine  drier 
Benzine  drier    .    .    . 
Water 

$  0.40 
1.00 
0.0326 
0  00 

68.9 

16\i 
15.0 

$27.56 

5.25 
0.00 

90.4 
9.4 

0.2 

$36.16 
9.40 

100  gallons  (750  pounds).  No.  I,  cost  $32.81. 
1  pound  costs  $0.0438. 

50.1  pounds  cost  $2.19. 

100  gallons  (750  pounds),  No.  II,  costs  $45.56. 
1  pound  costs  $0.0607. 

34.2  pounds  cost  $2.09. 


ANALYSIS  OF  WHITE   PAINTS. 
COST   OF   PIGMENT. 


127 


No.  I. 

No.  II. 

Pigment. 

Cost  per 
Lb. 

Lbs. 

Total 
Cost. 

Lbs. 

Total 
Cost. 

White  lead        .    .    . 

$0.065 

21.73 

$1.41 

49.53 

$3.22 

Lead  sulphate  l     .    . 

0.05 

0.85 

0.04 

0.44 

0.02 

Zinc  oxide     .... 

0.05 

47.89 

2.39 

49.64 

2.48 

Inert  pigments     .    . 

0.01 

27.39 

0.27 

Color 

0.05 

2.14 

0.11 

6.47 

0.02 

100  pounds  total  pigment,  No.  I,  cost  $4.22. 
1  pound  costs  $0.042. 
49.9  pounds  cost  $2.11. 

100  pounds  total  pigment,  No.  II,  cost  $5.74. 
1  pound  costs  $0.057. 
65.8  pounds  cost  $3.75. 

No.  I. 

50 . 1  pounds  liquid  cost $2.19 

49 . 9  pounds  pigment  cost 2.11 


100.0  pounds  paint  cost $4.30 

1 . 0  pound  paint  costs 0 . 043 

1  gallon  (2  pounds  14  ounces)  X  4  costs      .  0.495 

No.  II. 

34 . 2  pounds  liquid  cost $2 . 09 

65 . 8  pounds  pigment  cost 3 . 75 


100.0  pounds  paint  cost $5.84 

1  pound  paint  costs 0.0584 

1  gallon  (or  16  pounds  3  ounces)  costs     .    .       0.945 

In  other  words,  one  paint  costs  almost  exactly  twice  as 
much  as  the  other,  as  regards  paint  and  oil  ingredients. 
The  cost  of  the  can  (gallon  size),  label,  and  crate  is  about 
10  cents.  Salesmen's  commissions,  salary  and  travelling 
expenses  are  about  5  cents  per  gallon;  the  cost  of  manu- 
facture, depreciation  of  plant  and  machinery,  6  to  8  cents 
per  gallon. 

1  Lead  sulphate  present  in  the  zinc  oxide. 


128 


ANALYSIS  OF  MIXED  PAINTS. 


It  must  also  be  borne  in  mind  that  the  cost  of  crude 
materials  has  advanced  markedly  during  the  last  few 
years.  The  following  table  prepared  by  the  Paint  Manu- 
facturers' Association  shows  the  increase  in  cost  of  various 
paint  materials  in  1907,  as  compared  with  1897. 

Material.  Per  cent 

Increase  in  Cost. 

White  lead        61 .8 

Zinc  oxide         40 . 5 

Barium  sulphate      44 . 2 

Linseed  oil        45 .4 

Turpentine       155.0 

Japan  drier 42.0 

Tin  cans .   .       33.0 

Packing  boxes      64 . 2 

182.   ANALYSES  OF  SUBLIMED  LEAD  PAINTS  BY  AUTHOR. 

I. 

White. 

Net  weight,  Ibs.  and  oz.     .   15 
Capacity  of  can,  qts.  .    .    .3.96 
Contents,  qts 3 . 95 

Per  cent. 
57.0 
43.0 


Pigment  by  weight  . 
Vehicle  by  weight    . 


100.0 


II. 

III. 

IV. 

White. 

Pearl  Gray. 

White. 

15:  1 

14:8 

3:20 

4.00 

4.00 

1.03 

3.94 

3.86 

.95 

Per  cent. 

Per  cent. 

Per  cent. 

59.2 

58.6 

64.8 

40.8 

41.4 

35.2 

100.0 


100.0 


100.0 


Linseed  oil     .    . 

ANALYSIS  OF 

Per  cent. 
.    .    .    .         90.5 

VEHICLE. 

Per  cent. 
90.4 

Drier  

.    .    .    .           9.31 

9.5 

Water     .... 

.    .    .    .           0.2 

0.1 

100.00 

100.00 

Per  cent.  Per  cent. 

90.4  84.5 

9.6  6.4 

0.0  9.1 

100.00  100.00 


ANALYSIS  OF  PIGMENT. 


White  lead 

Lead  sulphate 2     .    .    .    . 

Lead  oxide 

Zinc  oxide 

Barium  sulphate  .... 
Undetermined  color,  etc., 


Per  cent.      Per  cent.     Per  cent.     Per  cent 


0.00 
58.37 

5.99 
35.24 

0.00 

0.40 

100.00 


0.00 
33.46 

9.63 
56.38 

0.00 

0.53 


0.00 
35.56 

8.93 
55.11 

0.00 

0.40 


Benzine. 


100.00         100.00 
2  Sublimed  lead. 


0.00 
59.09 
16.01 

5.18 
19.08 

0.64 

100.00 


ANALYSIS  OF  WHITE   PAINTS. 


129 


In  the  above  analyses  the  percentage  of  zinc  oxide  inci- 
dental to  the  manufacture  of  sublimed  lead  is  included  in 
the  total  zinc  oxide. 

183.  ANALYSES  OF  LEADED  ZINC  PAINTS  BY  AUTHOR. 

I.  II. 

Lead  White. 

Color. 

Net  weight,  Ibs.  and  oz 6:14  3:8 

Capacity  of  can,  qts 1.91         1.06 

Contents,  qts 1.82         1.00 


Pigment  by  weight  . 
Vehicle  by  weight     . 


Linseed  oil 
Benzine  drier 
Water 


Per  cent. 
58.9 
41.1 

100.00 


Per  cent. 
60.7 
39.3 

100.00 


III. 

Blue. 

0:14.5 
.33 

.28 
Per  cent. 
57.0 
43.0 


IV. 

Gray. 

5:10 

1.95 

1.70 

Per  cent. 

57.8 
42.2 


100.00         100.00 


ANALYSIS  OF  VEHICLE. 


80.2 

8.5 

11.3 


56.9 
20.6 
22.5 


60.4 
25.7 
13.9 


77.6 

7.9 

14.5 


100.00       100.00       100.00       100.00 


ANALYSIS  OF  PIGMENT. 


White  lead 

Lead  sulphate 

Zinc  oxide 

Calcium  carbonate    .    .    . 

Barytes 

Undetermined  color,  etc. 


Per  cent.  Per  cent.  Per  cent.  Per  cent. 


39.26 
34.20 

5.39 
19.90 

1.25 


18.13 

34.04 

41.09 

6.20 

0.54 


17.77 

33.58 

39.88 

6.40 

2.371 


14.23 

37.57 

41.70 

6.10 

0.40 


100.00       100.00       100.00       100.00 


184.   ANALYSES   BY  AUTHOR  OF   MIXED   PAINTS   FOR 
INSIDE  USE. 


I. 

Inside 
White. 
Net  weight,  Ibs.  and  oz.  .    .    .      3 :0 

Capacity  of  can,  qts 1 . 04 

Contents,  qts 0.99 

Per  cent. 

Pigment 62.9 

Vehicle  .  37.1 


II. 

Inside 
White. 
15:0 
0.30 
0.26 
Per  cent. 
28.3 
71.7 


100.00  100.00 

Color  largely  organic. 


100.00 


130 


ANALYSIS  OF  MIXED  PAINTS. 


VEHICLE. 


Linseed  oil     .... 

Per  cent. 
60  I1 

Per  cent. 
68  61 

Turpentine 

39  9 

30  0 

Water     ....... 

0.0 

1.4 

100.0 
PIGMENT. 

100.0 

White  lead 

Lead  sulphate 

Zinc  oxide      

Lithopone 

Barium  sulphate 20.12 

Zinc  sulphide 6.13 

Silica 

Undetermined  . 


Per  cent. 

77.9 

22.1 

0.0 

100.0 


Per  cent.   Per  cent.     Per  cent. 
18.84 
2.57 

70.27         99.80        80.45 
26.33 


0.28 
0.55 


0.20 


0.71 


100.00   100.00   100.00 


185.  Analyses  of  cheapened  mixed  paints  by  the  author, 
showing  the  various  devices  used  for  cheapening  the  cost 
of  production,  —  short  volume,  low  pigment  content, 
practical  absence  of  all  lead  pigments,  excessive  use  of 
drier,  high  per  cent  of  water  and  of  cheap  inerLpigments. 
Two  of  these  brands  were  sold  as  straight  white  lead  and 
zinc  oxide  paints. 


I.  II. 

White.  Gray. 

Net  weight,  Ibs.  and  oz 3:0  6:3 

Capacity  of  can,  qts.    .....    1.03  1.95 

Contents,  qts 99  1.92 


Pigment  by  weight  . 
Vehic 


licle 


Per  cent. 
55.1 
44.9 


Per  cent. 
54.6 
45.4 


III. 
Lead 
Color. 
9:9 
3.37 
2.42 

Per  cent. 
67.10 
32.90 


100.0  100.0         100.00 

l.  Includes  a  small  amount  of  dammar  varnish. 


IV. 

Slate 
Color. 
5:12 
1.90 
1.85 

Per  cent. 
50.8 
49.2 


100.0 


ANALYSIS   OF  WHITE   PAINTS. 


ANALYSIS  OF  VEHICLE. 


131 


Lins66(d  oil 

Per  cent. 
.    .    .     72.5 

Per  cent. 
54.  41 

Per  cent. 
83.  91 

Per  cent. 
61.9 

Benzine  drier    . 
Water 

.    .       9.1 
.    .      18.4 

28.9 
16.7 

4.3 

11.8 

22.0 
16.1 

100.00         100.00         100.00         100.00 

ANALYSIS  OF  PIGMENT. 

Per  cent.     Per  cent.      Per  cent.     Per  cent. 


White  lead     

Lead  sulphate  
Zinc  oxide      

.89 
53.86 

3.11 
24.67 

4.73 
24.34 

0.74 

60.10 

Calcium  carbonate   .    .    . 
Magnesium  carbonate 
Barytes 

43.39 
0.73 

40.07 
22.10 

4.47 
66.26 

21.11 

Silica 

0  60 

7.26 

16.25 

Undetermined  color,  etc. 

.53 

2.79 

0.20 

1.80 

100.00 


100.00         100.00 


100.00 


ANALYSIS   OF  WHITE  PAINTS  ACCORDING  TO  THOMPSON.1 

186.  Schemes  for  the  separation  of  the  constituents  from 
each  other  and  into  their  proximate  combinations  depend 
on  the  constituents  present,  and  we  can  treat  this  subject 
in  no  better  way  than  by  taking  typical  cases,  which  we 
now  do. 

187.  Sample  1  is  a  mixture  of  barytes,  white  lead,  and 
zinc  oxide. 

Two  1-gram  portions  are  weighed  out.  One  is  dis- 
solved in  acetic  acid  and  filtered,  the  insoluble  matter 
ignited  and  weighed  as  barytes,  the  lead  in  the  soluble 
portion  precipitated  with  bichromate  of  potash,  weighed 
in  Gooch  crucible  as  chromate,  and  calculated  to  white 
lead. 

The  other  portion  is  dissolved  in  dilute  nitric  acid, 
sulphuric  acid  added  in  excess,  evaporation  carried  to 
fumes,  water  added,  the  zinc  sulphate  solution  filtered 

1  Very  low  grade  linseed  oil. 

2  J.  Soc.  Chem.  Ind.,  June  30,  1896. 


132  ANALYSIS    OF    MIXED    PAINTS. 

from  barytes  and  lead  sulphate  and  precipitated  directly 
as  carbonate,  filtered,  ignited,  and  weighed  as  oxide. 

1 88.  Sample  2  is  a  mixture  of  barytes  and  so-called 
sublimed  white  lead. 

Weigh  out  three  1-gram  portions.  In  one  determine 
zinc  oxide  as  in  case  1.  Treat  a  second  portion  with  boil- 
ing acetic  acid,  filter,  determine  lead  in  filtrate  and  calcu- 
late to  lead  oxide.  Treat  third  portion  by  boiling  with 
acid  ammonium  acetate,  filter,  ignite,  and  weigh  residue 
as  barytes,  determine  total  lead  in  filtrate,  deduct  from  it 
the  lead  as  oxide,  and  calculate  the  remainder  to  sulphate. 
Sublimed  lead  contains  no  hydrate  of  lead,  and  its  relative 
whiteness  is  probably  due  to  the  oxide  of  lead  being  com- 
bined with  the  sulphate  as  basic  sulphate.  Its  analysis 
should  be  reported  in  terms  of  sulphate  of  lead,  oxide  of 
lead,  and  oxide  of  zinc. 

189.  Sample  3  is  a  mixture  of  barytes,  sublimed  lead,  and 
white  lead. 

Determine  barytes,  zinc  oxide,  lead  soluble  in  acetic 
acid  and  in  ammonium  acetate,  as  in  case  2;  also,  deter- 
mine carbonic  acid,  which  calculated  to  white  lead,  deduct 
lead  in  white  lead  from  the  lead  soluble  in  acetic  acid,  and 
calculate  the  remainder  to  lead, oxide. 

190.  Sample  4  is  a  mixture  of  barytes,  white  lead,  and 
carbonate  of  lime. 

Determine  barytes  and  lead  soluble  in  acetic  acid  (white 
lead)  as  in  case  1.  In  filtrate  from  lead  chromate  precipi- 
tate lime  as  oxalate,  weigh  as  sulphate,  and  calculate  to 
carbonate.  Chromic  acid  does  not  interfere  with  the  pre- 
cipitation of  lime  as  oxalate  from  acetic  acid  solution. 

191.  Sample  5  is  a  mixture  of  barytes,  white  lead,  zinc 
oxide,  and  carbonate  of  lime. 

Determine  barytes  and  white  lead  as  in  case  1.  Dis- 
solve another  portion  in  acetic  acid,  filter  and  pass  sul- 


ANALYSIS  OF  WHITE   PAINTS.  133 

phuretted  hydrogen  through  the  boiling  solution,  filter, 
and  precipitate  lime  in  filtrate  as  oxalate;  dissolve  mixed 
sulphides  of  lead  and  zinc  in  dilute  nitric  acid,  evaporate 
to  fumes  with  sulphuric  acid,  separate,  and  determine  zinc 
oxide  as  in  case  1. 

192.  Sample  6  is  a  mixture  of  barytes,  white  lead,  sub- 
limed lead,  and  carbonate  of  lime. 

Determine  barytes,  lead  soluble  in  acetic  acid  and  in 
ammonium  acetate,  as  in  case  2,  lime  and  zinc  oxide,  as  in 
case  5,  and  carbonic  acid.  Calculate  lime  to  carbonate  of 
lime,  deduct  carbonic  acid  in  it  from  total  carbonic  acid, 
calculate  the  remainder  of  it  to  white  lead,  deduct  lead  in 
white  lead  from  lead  soluble  in  acetic  acid,  and  calculate 
the  remainder  to  oxide  of  lead. 

193.  Sample  8  contains    as  insoluble    matter,  barytes, 
china  clay,  and  silica. 

After  igniting  and  weighing  the  insoluble  matter,  car- 
bonate of  soda  is  added  to  it,  and  the  mixture  fused.  The 
fused  mass  is  treated  with  water,  and  the  insoluble  portion 
filtered  off  and  washed.  This  insoluble  portion  is  dis- 
solved in  dilute  hydrochloric  acid,  and  the  barium  present 
precipitated  with  sulphuric  acid  in  excess.  The  barium 
sulphate  is  filtered  out,  ignited,  weighed,  and  if  this  weight 
does  not  differ  materially  —  say  by  2  per  cent  —  from  the 
weight  of  the  total  insoluble  matter,  the  total  insoluble 
matter  is  reported  as  barytes.  If  the  difference  is  greater 
than  this,  add  the  filtrate  from  the  barium  sulphate  pre- 
cipitate to  the  water-soluble  portion  of  fusion.  Evaporate 
and  determine  the  silica  and  the  alumina  in  the  regular 
way.  Calculate  the  alumina  to  China  clay  on  the  arbi- 
trary formula  2Si02,  A1203,  2H20,  and  deduct  the  silica  in 
it  from  the  silica,  reporting  the  latter  in  a  free  state.  It 
is  to  be  borne  in  mind  that  China  clay  gives  a  loss  of  about 
13  per  cent  on  ignition,  which  must  be  allowed  for.  China 


134  ANALYSIS  OF  MIXED   PAINTS. 

clay  is  but  slightly  used  in  white  paints  as  compared  with 
barytes  and  silica. 

194.  Sample  9  contains  sulphide  of  zinc. 

Samples  of  this  character  are  usually  mixtures  in  vary- 
ing proportions  of  barium  sulphate,  sulphide  of  zinc, 
and  oxide  of  zinc.  Determine  barytes  as  matter  insol- 
uble in  nitric  acid,  the  total  zinc  as  in  case  1,  and  the  zinc 
soluble  in  acetic  acid,  which  is  oxide  of  zinc.  Calculate 
the  zinc  insoluble  in  acetic  acid  to  sulphide. 

195.  Sample  10  contains  sulphite  of  lead. 

This  is  of  rare  occurrence.  Sulphite  of  lead  is  insoluble 
in  ammonium  acetate,  and  may  be  filtered  out  and  weighed 
as  such.  It  is  apt  on  exposure  to  the  air  in  the  moist 
state  to  become  oxidized  to  sulphate  of  lead. 

There  are  certain  arbitrary  positions  which  the  chemist 
must  take  in  reporting  analyses  of  white  paints:  — 

1st.  White  lead  is  not  uniformly  of  the  composition 
usually  given  as  theoretical  (2PbC03),  (PbH2O2),  but  in 
reporting  we  must  accept  this  as  the  basis  of  calculating 
results,  unless  it  is  demonstrated  that  the  composition  of 
the  white  lead  is  very  abnormal. 

2d.  In  reporting  oxide  of  lead  present  this  should  not 
be  done  except  in  the  presence  of  sulphate  of  lead,  and 
if  white  lead  is  present,  then  only  where  the  oxide  is  more 
than  one  per  cent;  otherwise  calculate  all  the  lead  soluble 
in  acetic  acid  to  white  lead. 

3d.  China  clay  is  to  be  calculated  to  the  arbitrary 
formula  given. 

In  outlining  the  above  methods  we  have  in  mind  many 
samples  that  we  have  analyzed,  and  the  combinations  we 
have  chosen  are  those  we  have  actually  found  present. 


CHAPTER  XI. 

ANALYSIS    OF  INDIAN    REDS,  VENETIAN    REDS,    TUSCAN 
REDS,    RED    OXIDES,    AND    OCHRES. 

196.  Hygroscopic   moisture.     Heat  2  grams  at   105°  C. 
for  3  hours.     Loss  in  weight  represents  hygroscopic  mois- 
ture. 

197.  Combined  water,  etc.    Transfer  above  sample  to  a 
weighed  platinum  crucible  and  heat  for  one  hour  over  an 
ordinary  lamp,  or  better  in  a  muffle.    Loss  in  weight  indi- 
cates amount  of  combined  water.     Carbonates  and  organic 
matter  render  the  results  inaccurate,  in  which  case  con- 
tinue the  ignition  at  bright  red  heat  for  several  hours,  and 
weigh  again.     Determine  the  carbon  dioxide  in  another 
portion  of  the  sample  and  estimate  the  combined  water 
by  difference.     If  a  large  amount  of  calcium  sulphate  is 
present,  it  is  possible  to  heat  it  strongly  enough  to  par- 
tially drive  off  the  combined  sulphuric  acid,  and  unless  this 
be  taken  account  of  the  analysis  will  total  up  to  more  than 
100  per  cent.     In  the  case  of  a  Tuscan  red  which  has 
precipitated  upon  it  an  organic  color,  the  loss  in  weight 
is  best  reported  as  combined  water  and  organic  matter. 
The  presence  of  an  organic  color  may  always  be  detected 
by  the  characteristic  odor  given  off  at  the  beginning  of 
the  ignition. 

198.  Silica   and    barium    sulphate.     One   gram   of   the 
pigment  is  intimately  mixed  with  6  to  8  grams  of  potas- 
sium bisulphate  and  fused  in  a  large  porcelain  crucible, 

135 


136  ANALYSIS  OF  MIXED  PAINTS. 

the  cover  of  which  is  small  enough  to  set  inside  the  top 
of  the  crucible,  at  not  too  high  a  temperature  for  one-half 
hour,  finally  heating  the  side  of  the  crucible  to  finish 
the  conversion  of  any  material  adhering  to  the  cover  and 
upper  portion  of  the  crucible.  The  iron,  aluminum, 
calcium,  and  magnesium  are  converted  into  sulphates,  the 
barytes  remains  unchanged  and  the  silica  is  completely 
dehydrated.  With  a  little  care,  using  a  low  heat  at  first, 
the  fusion  may  be  conducted  with  very  little  frothing  or 
spattering.  Fusion  with  bisulphate  is  to  be  preferred  to 
solution  with  hydrochloric  acid,  as  ferric  chloride  is 
appreciably  volatile  on  boiling.  Also  the  silicates  of  iron 
that  are  present  in  small  quantity  in  the  natural  oxides 
are  not  decomposable  with  hydrochloric  acid. 

After  cooling,  the  entire  contents  of  the  crucible  may  be 
shaken  loose  and  dissolved  in  sufficient  water  and  a  little 
hydrochloric  acid.  Filter  and  make  up  to  250  c.c.  unless 
calcium  is  present  in  large  amount,  in  which  case  make 
up  to  a  volume  of  not  less  than  500  c.c.  as  calcium  sulphate 
is  but  sparingly  soluble. 

The  residue  remaining  on  the  filter  is  ignited  and  weighed 
in  a  platinum  crucible.  The  residue  is  tested  for  barium 
sulphate  by  the  flame  test:  if  absent  the  residue  is  reported 
as  silica;  if  present  the  residue  is  treated  in  the  crucible 
with  hydrofluoric  acid  until  a  thin  paste  is  formed.  The 
mixture  is  stirred  with  a  platinum  wire  and  digested  at  a 
gentle  heat;  finally  two  or  three  drops  of  sulphuric  acid 
are  added,  and  the  temperature  gradually  raised  until  no 
further  loss  in  weight  takes  place,  indicating  that  the 
silica  has  been  completely  expelled.  The  residue  is 
weighed  as  barium  sulphate,  and  the  loss  in  weight  repre- 
sents the  silica,  or,  the  residue  of  barium  sulphate  and 
silica  may  be  fused  with  sodium  carbonate  as  described 
under  the  analysis  of  white  pigments. 


ANALYSIS  OF  INDIAN  REDS.  137 

199.  Ferric  oxide.    An  aliquot  portion  of  the  solution 
from  198  is  heated  to  boiling,  and  stannous  chloride  solu- 
tion added  cautiously  until  the  yellow  color  has  disap- 
peared, and  then  a  slight  excess  added.    All  at  once  with 
vigorous  shaking  of  the  flask,  50  c.c.  of  mercuric  chloride 
solution  is  added,  then  50  c.c.  of  the  manganous  sulphate 
solution.     Dilute  with  cold  fresh  boiled  water  and  titrate 
with    permanganate    solution.     Calculate    iron    found    to 
ferric  oxide. 

200.  Preparation  of  Reagents. 

a.  Stannous   chloride.     Dissolve    30    grams    of    tin   in 
250  c.c.  of  hydrochloric  acid,  filter  through  glass  wool,  and 
make  up  to  one  litre. 

b.  Mercuric  chloride.     Dissolve  50  grams  in  one  litre. 

c.  Manganous  sulphate.    One  litre  should  contain  66.7 
grams  of  crystallized  manganous  sulphate,  333  c.c.  phos- 
phoric acid  (Sp.  Gr.  1.3)  and  133  c.c.  of  cone,  sulphuric 
acid. 

d.  Potassium   permanganate.    Dissolve   3.16   grams   in 
one  litre;  standardize  against  the  standard  iron  solution. 

e.  Standard   iron   solution.     Dissolve    7.03   grams   iron 
wire,  99.7  per  cent  purity,  in  dilute  hydrochloric  acid; 
make  to  one  litre. 

1  c.c.  =  0.01  g.  ferric  oxide  or  0.007  gr.  iron. 

In  many  cases  where  a  rapid  commercial  determination 
of  the  iron  content  alone  is  desired,  the  pigment  may  be 
dissolved  in  hydrochloric  acid,  with  the  subsequent  addition 
of  a  few  drops  of  nitric  acid,  filtered,  the  iron  and  alumina 
precipitated  with  ammonia;  after  thorough  washing  dis- 
solved in  sulphuric  acid,  run  through  a  "reductor,"  such 
as  may  be  obtained  from  any  of  the  leading  supply  houses, 
and  then  simply  titrated  with  standard  permanganate 
solution  in  the  usual  manner. 


138  ANALYSIS  OF  MIXED   PAINTS. 

201.  Alumina.    An  aliquot  part  of  the  solution  in  198 
is  made  just  alkaline  with  ammonia,   boiled,  decanted, 
filtered,     washed,     redissolved,     reprecipitated,    filtered, 
ignited  and  weighed  as  alumina  and  ferric  oxide,  the  alu- 
mina being  obtained  by  difference. 

202.  Calcium.    The  filtrate  from  the  iron  and  alumina 
is  treated  with  ammonium  oxalate  (50  c.c.  is  sufficient  for 
one  gram  of  calcium  pigment).     Set  aside   in   a   warm 
place  for  two  or  three  hours,  filter,  ignite,  and  weigh  as 
calcium  oxide,  or  titrate  with  standard  permanganate,  as 
may  be  desired.    The  calcium  may  have  been  present  as 
carbonate  or  sulphate  or  both.     Hence  an  estimation  of 
the  sulphur  trioxide   present  in  the   original   sample   is 
necessary.     For  this  purpose  1  gram  is  dissolved  in  30  c.c. 
of  strong  hydrochloric  acid,   boiled   10  minutes,  diluted 
with  50  c.c.  of  water,  heated  to  boiling,  filtered,  and  washed 
with  hot  water.     Neutralize  the  filtrate  with  ammonia, 
then  make   just  distinctly  acid   with  hydrochloric  acid, 
boil,  add   10  c.c.  of  barium  chloride  solution,   continue 
boiling  for  10  minutes,  filter,  wash,  ignite  and  weigh  as 
barium    sulphate.     Calculate    sulphur    trioxide    by    mul- 
tiplying weight  of  precipitate  by  0.343. 

Calculate  the  sulphur  trioxide  found  to  calcium  sul- 
phate and  the  remaining  calcium  to  oxide,  provided  that 
the  carbon  dioxide  is  included  under  loss  on  ignition.  If 
desired,  the  remaining  calcium  may  be  calculated  to 
calcium  carbonate,  the  combined  carbon  dioxide  being 
deducted  from  the  loss  on  ignition. 

203.  Magnesium.     If  a  considerable  percentage  of.  cal- 
cium is  found,  magnesium  is  liable  to  be  present,  precipi- 
tate with  sodium  hydrogen  phosphate  in  usual  manner. 
Calculate  the  pyrophosphate  to  oxide  by  multiplying  by 
the  factor  0.3624. 


ANALYSIS   OF  INDIAN   REDS. 


139 


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140  ANALYSIS  OF  MIXED  PAINTS. 

205.  Tuscan   reds   should   contain   about   60   per  cent 
ferric  oxide,  and  are  often  brightened  up  by  having  pre- 
cipitated  on   them    an   organic   red.    Another   class   of 
oxides,  carrying  about  the  same  amount  of  iron  oxide  as 
Tuscan   reds,   is    "Prince's   metallic."    The   variation   of 
iron  content  is  shown  in  the  following  analyses: 

No.                                                        Ferric  Oxide. 
I 44.07 

II 38.17 

III 68.45 

IV 49.58 

V 39.35 

A  complete  analysis  gave  the  following  : 

Per  cent. 

Volatile 3  .33 

Ferric  Oxide   40 .91 

Alumina 3 .49 

Calcium  Oxide 2 .00 

Insoluble 49  .57 

Undetermined 0.70 

100.00 

206.  Ochres,  of  which  the  French  ochres  are  considered 
the  best,  to  pass  inspection  by  the  various  service  depart- 
ment scientists  of  the  United  States  Government,  must  be 
of  good  bright  color,  contain  at  least  20  per  cent  sesqui- 
oxide  of  iron  and  not  over  5  per  cent  of  lime  in  any  form. 
A  good  grade  of  yellow  ochre  to  pass  this  inspection  would 
analyze  about  as  follows  :  — 

Per  cent. 

Silica 52.14 

Alumina 12.89 

Ferric  oxide 22.42 

Calcium  oxide 0 . 36 

Combined  water 10.16 

Hygroscopic  water 2.03 

100.00 


ANALYSIS   OF  INDIAN   REDS. 


141 


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142  ANALYSIS  OF  MIXED  PAINTS. 

Specifications  for  Venetian  Red. 

(Bureau  of  Supplies  and  Accounts,   Navy  Department,   1902). 

208.  Red,  Venetian.  I.  Red,  Venetian  (bright).  The 
dry  pigment  must  contain  at  least  20  per  cent  of  sesqui- 
oxide  of  iron,  not  more  than  15  per  cent  of  silica,  the 
balance  to  consist  of  sulphate  of  lime  that  has  been  fully 
dehydrated  by  dead  burning,  and  rendered  incapable  of 
taking  up  water  of  crystallization. 

II.  Red,    Venetian    (deep).     The    dry    pigment    must 
contain  at  least  30  per  cent  of  sesquioxide  of  iron,  not 
more  than  15  per  cent  of  silica,  the  balance  to  consist  of 
sulphate  of  lime  that  has  been  fully  dehydrated  by  dead 
burning  and  rendered  incapable  of  taking  up  water  of 
crystallization. 

III.  Red,  Venetian  (medium).    The  dry  pigment  must 
contain  at  least  40  per  cent  of  sesquioxide  of  iron,  not 
more  than  15  per  cent  of  silica,  the  balance  to  consist  of 
sulphate  of  lime  that  has  been  fully  dehydrated  by  dead 
burning  and  rendered  incapable  of  taking  up  water  of 
crystallization. 


CHAPTER  XII. 

ANALYSIS  OF  BLACK  AND  BROWN  PIGMENTS  AND  PAINTS. 

209.  Composition.  The  ordinary  black  pigments,  lamp- 
black, vegetable  black,  bone  black,  ivory  drop  black,  gas 
black,  graphite,  etc.,  contain  carbon  as  their  essential  con- 
stituent, and  while  all  of  these  products  are  said  to  be  of 
a  black  color,  they  vary  greatly  in  shade  and  still  more  so 
in  tinting  strength. 

1.  Lampblack  and  vegetable  black  are  essentially  soot 
blacks,  being  the  soot  deposited  from  the  combustion  of 
oily  bodies  such  as  dead  oil.     Lampblack  has  a  distinct 
gray  tint  as  may  be  shown  by  comparison  with  ivory 
black.    These  blacks  are  apt  to  contain  varying  quanti- 
ties of  oil,  owing  to  the  nature  of  their  manufacture. 
Less  than  1  per  cent  of  oil  often  being  sufficient  to  retard 
seriously  the  drying  of  lampblack  paints.    Vegetable  blacks 
are  more  voluminous    than    lampblacks  and  are  usually 
of  a  jet  black  color. 

2.  Carbon  black  is  usually  produced  from  the  incom- 
plete combustion  of  natural  gas.    While  its  tinting  power 
is  very  great  its  use  has  been  largely  abandoned  owing  to 
its  tendency  to  produce  a  streaky  color  when  used  in 
tinting  paints. 

3.  Bone    black  is  as  its  name  indicated,  obtained  by 
the  charring  of  bones  in  retorts.     The  carbon  content 
varies  usually  between  12  and  22  per  cent,  the  balance 
consisting  of   moisture,   phosphate   of  calcium   and  car- 
bonate of  calcium.    The  best  grades  of  bone  black  are 
made  from  selected  sheep  bones.    An  exceedingly  intense 

143 


144  ANALYSIS  OF  MIXED   PAINTS. 

black  is  made  by  digesting  selected  bones  in  hydrochloric 
acid  until  all  of  the  mineral  matter  is  dissolved,  leaving 
the  carbon  in  a  flocculent  state.  This  black  is  often  sold 
under  the  name  of  black  toner,  and  is  one  of  the  highest 
priced  blacks. 

4.  Animal  black  is  a  name  sometimes  given  to  bone 
black  but  is  also  used  to  designate  a  wide  variety  of  blacks 
prepared  in  the  same  way  as  bone  black  from  waste  animal 
products  of  all  kinds,  as  leather  scrap  parings,  horn  trim- 
mings, etc. 

5.  Frankfort    black,    drop-black    and    German    black 
are    terms    used    to    designate    blacks     made     from    a 
variety     of     organic     materials,     such     as    vine     twigs, 
refuse    of    wine-making,    peach    stones,    bone    shavings, 
etc.      These    blacks    vary    in   hue   from   a   bluish-black 
to  a  reddish-black. 

6.  Graphite  while  not  used  to  any  extent  in  house- 
paints  is  largely  used  in  bridge,  elevator,  and  warehouse 
paints.     It  is  rarely  used   by  itself  for  these   purposes, 
silica,  calcium  carbonate  and  iron  oxide  pigments,  zinc 
and  lead  being  the  other  usual  constituents.     It  may  be 
tested  for  qualitatively  in  the  extracted  pigment  by  rub- 
bing a  portion  of  the  sample  between  the  palms,  which 
soon  assume  the  characteristic  appearance  produced  by 
stove  polish.     Of  all  the  black  pigments  graphite  alone 
gives  this  test. 

7.  Charcoal  black  and  vine  black  are  produced  by  the 
charring  of  wood  products,  and  contain  besides  carbon  the 
ash  ingredients  common  to  wood.      Charcoal  blacks  are 
usually  made  from  maple,  willow  and  bass  wood,  and  vine 
blacks  from  the  charring  of  the  grape  vine.      Paints  con- 
taining considerable  quantities  of  these  blacks  are  liable  to 
saponify  badly  owing   to   the    moisture  and  potash  salts 
present. 


BLACK  AND  BROWN   PIGMENTS.  145 

8.   Mineral    black    which   is   still   occasionally   used    is 
black  slate  finely  ground. 

210.  Moisture.     Dry  2  grams  at  105°  C.   for  3  hours. 
Loss  in  weight  represents  approximately  the  amount  of 
moisture  present. 

211.  Oils.    Extract  2  grams  with  ether  in  a  fat  extrac- 
tion  apparatus.     After  removing  the  ether  and   drying, 
any   increase   in   weight  represents   the   amount  of  oily 
matter  present. 

212.  Ash.    Two  grams  are  weighed  into  a  crucible  and 
heated  over  a  Bunsen  burner  until  all  the  carbon  is  burned 
off.    If  the  ash  constitutes  only  a  small  per  cent,  it  may 
be  cooled  and  weighed  directly.     Otherwise  the  residue 
is  moistened   with  a  solution  of  ammonium   carbonate, 
heated  gently,  and  weighed.    The  object  of  this  operation 
is   to   restore  the  carbon  dioxide  which   may   have  been 
expelled  from  the  bases  by  the  strong  heat  to  which  they 
have  been  subjected. 

213.  Carbon.    The    carbon    is    usually    estimated    by 
difference,  by  adding  together  the  moisture,  oil  and  ash, 
and  subtracting  from  100. 

214.  Calcium.     Digest  the  residue  from  212  in  a  mix- 
ture of  25  c.c.  of  concentrated  hydrochloric  acid  and  5.c.c. 
of  concentrated  nitric  acid  on  the  hot  plate  for  one-half 
hour,  dilute,  filter,  and  make  up  to  250  c.c.  in  a  graduated 
flask.    Any  appreciable  residue  on  the  filter  may  indicate 
addition  of  barytes,  silica,  clay  or  alumina.      Determine 
the  calcium  and  magnesium  in  an  aliquot  portion  of  the 
solution  by  adding  ammonia  in  small  quantities  until  a 
precipitate   is  formed,  then  acetic  acid   in  excess   until 
redissolved,  except  for  traces  of  iron  which  may  be  re- 
moved by  filtration.    Ammonium  oxalate  is  added,  and 
the  calcium  precipitate  treated  in  the  usual  manner. 

215.  Phosphoric     acid.     Take   an    aliquot    portion  of 


146  ANALYSIS  OF  MIXED   PAINTS. 

the  solution  prepared  above,  neutralize  with  ammonia,  and 
clear  with  a  few  drops  of  nitric  acid,  add  about  5  grams 
of  dry  ammonium  nitrate  or  a  solution  containing  that 
amount.  To  the  hot  solution  add  50  c.c.  of  molybdic 
solution  for  every  decigram  of  phosphoric  acid  that  is 
present.  Digest  at  about  65°  for  an  hour,  filter  and  wash 
with  cold  water,  or  preferably  ammonium  nitrate  solution. 
Test  the  filtrate  for  phosphoric  acid  by  renewed  digestion 
and  addition  of  more  molybdic  solution.  Dissolve  the 
precipitate  on  the  filter  with  ammonia  and  hot  water,  and 
wash  into  a  beaker  to  a  bulk  of  not  more  than  100  c.c. 
Nearly  neutralize  with  hydrochloric  acid,  and  add  mag- 
nesia mixture  from  a  burette;  add  slowly  (about  1  drop 
per  second),  stirring  vigorously.  After  15  minutes  add 
30  c.c.  of  ammonia  solution  of  density  0.96.  Let  stand 
for  some  time;  2  hours  is  usually  enough.  Filter,  wash 
with  2.5  per  cent  ammonia,  ignite  to  whiteness  or  to  a 
grayish  white,  and  weigh  as  magnesium  pyrophosphate. 

216.  Preparation  of  reagents.     Molybdic  solution.     Dis- 
solve 100  grams  of  molybdic  acid  in  400  grams  or  417  cc., 
of  ammonia,  specific  gravity  0.96,  and  pour  the  solution 
thus  obtained  into  1,500  grams  or  1,250  c.c.  of  nitric  acid, 
specific  gravity  1.20.     Keep  the  mixture  in  a  warm  place 
for  several  days,  or  until  a  portion  heated  to  40°  deposits 
no   yellow   precipitate.     Decant   the   solution    from   any 
sediment  and  preserve  it  in  glass-stoppered  vessels. 

Magnesia  Mixture.  Dissolve  110  grams  of  crystallized 
magnesium  chloride,  280  grams  of  ammonium  chloride, 
in  700  c.c.  of  ammonia  of  specific  gravity,  0.96,  and  suffi- 
cient water  to  make  2000  c.c. 

217.  Magnesium.    The  filtrate,  from  which  the  calcium 
has  been  precipitated,  is  evaporated  to  a  small  bulk  and 
made    alkaline    with    ammonia.    After    standing  several, 
hours  the  magnesium  precipitate  is  filtered,  ignited,  and 


BLACK  AND   BROWN  PIGMENTS.  147 

weighed,   and   calculated   to   magnesium   by   multiplying 
by  21.88. 

218.  Calculations.    The    magnesium    is    calculated    to 
magnesium  phosphate,  and  the  remainder  of  the  phos- 
phoric acid  to  calcium  phosphate.     Any  calcium  remain- 
ing is  calculated  to  calcium  carbonate. 

Genuine  ivory  black,  made  by  carbonizing  waste  frag- 
ments and  turnings  of  ivory,  is  often  adulterated  with 
bone  black,  which  is  somewhat  similar  in  composition,  but 
contains  only  a  small  amount  of  magnesium  phosphate 
as  compared  with  the  ivory  black. 

219.  Specifications  for  drop  black.     (Navy  Department, 
May,  1903).     Drop  black  must  be  of  good  deep  luster  and 
consist  of  calcined  bone  black  only.     The  addition  of  blue 
or  gas  carbon  black  will  be  ground  for  rejection.    The  paste 
must  contain  not  less  than  45  per  cent  of  pure  pigment. 

The  pigment  must  be  of  the  best  quality,  free  from  all 
adulterants,  and  equal  in  all  respects  to  the  standard  sample. 

The  paste  must  be  ground  in  pure  raw  linseed  oil  only,  to 
a  medium  stiff  paste,  which  will  break  up  readily  in  thinning. 

220.  Specifications    for    carbon    black,    etc.     (Treasury 
Department,  1907).     Carbon  black  must  be  pure  gas  carbon 
with  not  more  than  0.5  per  cent  of  ash,  that  is,  97.5  per  cent 
of  pure  carbon  and  the  balance  moisture,  ash,  etc. 

Hard  black;  should  be  suitable  for  making  the  highest 
class  of  plate  printing  inks;  and  other  factors  being  equal, 
a  color  having  chemical  and  physical  properties  adapted 
for  that  purpose  and  which  produces  an  ink  having  the 
most  satisfactory  working  qualities  will  be  selected.  The 
black  now  in  use  has  the  following  chemical  analysis: 

Per  cent. 

Ash 48.3 

Moisture 3.7 

Carbon 48.0 

Ash  insoluble  in  hydrochloric  acid  11.4  per  cent. 


148 


ANALYSIS  OF  MIXED  PAINTS. 


Soft  Black.     Requirements  same  as  for  hard  black, 
black  in  use  has  the  following  chemical  analysis: 

Per  cent. 

Ash 56.1 

Moisture 2.5 

Carbon  (by  diff.) 41.4 

100.0 
Ash  insoluble  in  hydrochloric  acid  36.3  per  cent. 


The 


221.   COMPOSITION  OF  IVORY  AND   BONE. 


IVORY  (Uncalcined). 


Calcium  phosphate,  including  slight 
amount  of  calcium  fluoride     . 

Calcium  carbonate 

Magnesium  phosphate 

Soluble  salts      

Organic  matter 


BONE  (Uncalcined). 


Calcium  phosphate  .  . 
Calcium  carbonate  .  . 
Magnesium  phosphate. 
Organic  matter .  .  .  . 


I. 

Per  cent. 

38.48 
5.63 

12.01 
0.70 

43.18 

100.00 


I. 

Per  cent. 

61.4 
8.6 
1.7. 

28.3 

100.00 


II. 

Per  cent. 

46.48 
3.86 
7.84 
0.77 

41.05 

100.00 


II. 

Per  cent. 
62.4 

7.9 

1.7 
28.0 

100.00 


222.   TYPICAL   ANALYSES  BY  THE  AUTHOR  OF  THE 
VARIOUS   BLACKS. 


Moisture 
Oil  .  .  . 
Ash.  .  . 
Carbon  . 


I. 

Ivory  Drop 

Black 

Per  cent. 

0.14 

0.22 

15.23 

84.41 


100.00 


II. 

Lamp 

Black 

Per  cent. 

2.24 

0.35 

0.32 

97.09 

100.00 


III. 

Lamp 

Black 

Per  cent. 

2.18 

0.19 

0.10 

97.53 

100.00 


BLACK  AND  BROWN  PIGMENTS.  149 


I. 

II. 

III. 

Ivory 
Black  1 
Per  cent. 

German  Ivory 
Black 
Per  cent. 

Ivory 
Black  ' 
Per  cent. 

0.75 
0.17 

88.98 
0 

.42 

2.33 
0.22 

84.82 
0 

2.59 
0.14 

84.70 
32 

77 

.51 

77, 

,82 

6 

.51 

5 

,60 

0 
10.10 

.38 

0 
12.63 

96 
12.57 

100.00 

100.00 

100.00 

Moisture 

Oil 

Ash 

Insoluble      ...     0.88 
Calcium  phos- 
phate       .    .    .73.72 
Calcium  carbon- 
ate         14.00 

Magnesium  phos- 
phate   ....     0.38 
Carbon 


Analysis  of  Mixed  Paints  Tinted  with  Black  and 
Oxide  of  Iron  Pigments. 

223.  Carbon.     One  gram  of  the  pigment  is  dissolved 
in  hydrochloric  acid  as  described  under  white  pigments, 
and  the  residue  filtered  through  an  ashless  filter,  that  has 
been  dried  in  the    hot  water  oven  and  weighed.    After 
washing  the   residue   with   boiling   water   the   filter   and 
contents  are  dried  and  weighed,  then  ignited  until  all  the 
carbon  is  burned  off,  and  weighed  again.    The  percentage 
of   carbon    is   obtained    by  difference.     Where   the    per- 
centage of  color  is  small,  it  is  often  estimated  by  difference, 
adding   together   the   determined   constituents   and    sub- 
tracting from  100. 

224.  Ferric   oxide.     If   the   filtrate  from   the   insoluble 
residue  is  of  an  appreciable  yellow  color  it  indicates  that 
the  tint  has  been  "  warmed  up  "  by  the  addition  of  an 
ochre  or  oxide.     In  which  case  the  lead  is  precipitated 
and  estimated  as  described  under  analysis  of  white  pig- 
ments, the  filtrate  from  the  lead  sulphide  heated  until  all 
of  the  hydrogen  sulphide  has  been  expelled  and  the  iron 

1  Not  true  ivory  blacks. 


150  ANALYSIS  OF  MIXED  PAINTS. 

and  alumina  precipitated  with  ammonia  after  having 
been  oxidized  by  boiling  with  a  few  drops  of  nitric  acid, 
filtered  and  ignited  and  weighed  in  a  porcelain  crucible, 
the  residue  fused  with  bisulphate  of  potassium,  dissolved 
in  water  with  the  aid  of  a  little  hydrochloric  acid,  heated  to 
boiling,  reduced  with  stannous  chloride;  mercuric  chloride 
and  manganous  sulphate  solution  added  and  titrated  with 
permanganate  in  the  manner  described  under  analysis 
of  Venetian  Reds. 

225.  Alumina.    The  alumina  is  calculated  by  difference 
from  the  data  obtained  under  224. 

226.  Zinc  oxide.     The  filtrate  from  the  iron  and  alumina 
precipitate  and  the  filtrate  from  the  lead  sulphate  precipi- 
tate, the  alcohol  having  been  removed  by  evaporation,  are 
mixed,  made  distinctly  alkaline  with  ammonia  and  the 
zinc    precipitated    with    hydrogen    sulphide.     The    liquid 
containing  the  zinc  sulphide  precipitate  is  heated  to  boil- 
ing, and  about  5  grams  of  solid  ammonium  chloride  added, 
which  renders  the  precipitate  easier  to  filter.    Settle,  filter, 
and  wash  thoroughly.     Pierce  filter,  wash  through  into  a 
clean  beaker  with  water,  dissolving  the  residue  on  filter 
with  dilute  hydrochloric  acid  and  wash  with  hot  water. 
Dilute,  heat  to  expel  hydrogen  sulphide  arid  titrate  with 
ferrocyanide  as  previously  described.     If  iron  is  absent  in 
the  paint  the  zinc  may  be  estimated  directly  as  described 
under  analysis  of  white  paints. 

227.  Calcium  and  magnesium.     Estimate   as  usual   in 
the  filtrate  from  the  zinc  sulphide. 

228.  Residue  insoluble  in  hydrochloric  acid.     Fuse  with 
sodium  carbonate  as  previously  described.     Dissolve  in 
water  and  filter.     Iron  not  previously  dissolved  will  remain 
on  the  filter  as  ferric  oxide  along  with  any  barium  that  may 
be  present.     This  residue  after  thorough  washing  is  dis- 
solved with  the  aid  of  a  small  quantity  of  hydrochloric 


BLACK  AND  BROWN  PIGMENTS.  151 

acid,  the  barium  precipitated  as  usual  and  the  iron  esti- 
mated in  the  filtrate  from  the  barium  sulphate.  The 
silica  and  alumina  are  estimated  as  usual. 

229.  Lead  sulphate.  Determine  the  combined  sulphuric 
acid  as  described  under  analysis  of  white  paints  and  calcu- 
late to  lead  sulphate  in  the  absence  of  calcium  sulphate. 
If  calcium  carbonate  and  calcium  sulphate  are  both  present 
the  nitric  acid-alcohol  separation  should  be  used. 

230.   ANALYSES    BY    AUTHOR    OF    PAINTS    TINTED    WITH 
BLACKS,  OCHRE  AND  IRON  OXIDES. 

I.  II. 

Light  Drab.  Drab. 

Net  weight,  Ibs.  and  oz. 6:6  6:12 

Capacity  of  can,  qts 2.06         2.03 

Contents  qts 1.93         1.92 

Per  cent.       Per  cent. 

Pigment  by  weight  .  56 . 6  56 . 9 

Vehicle  .  43.4  43.1 


ICO. 00  100.00 

ANALYSIS  OF  VEHICLE. 

Per  cent.  Per  cent. 

Linseed  oil 92.9  92.0 

Turpentine  drier 7.0  6.2 

Water                                                                       0.1  1.8 


100.00         100.00 

ANALYSIS  OF  PIGMENT. 

Per  cent.  Per  cent. 

White  lead 26.57  27.73 

Lead  sulphate   .    . 0.78  2.39 

Zinc  oxide 62.34  57.12 

Color 10.31  12.76 

Clay  and  silica 5 . 56  7 . 74 

Iron  oxide      3 . 02  3 . 89 

Carbon  and  undetermined  .  1.73  1.13 


100.00  100.00 


152  ANALYSIS  OF  MIXED  PAINTS. 

Vandyke-Brown.     Composition. 

231.  Vandyke-Browns     vary     widely    in     composition 
according    to    the    method    of   preparation.      Some    are 
obtained    from  natural  deposits   of    an    organic    nature, 
such  as  peat,  decayed  vegetable  matter,  etc. ;  or    by  the 
slight  calcining  of  cork-cuttings,  bark  and  twigs  of  trees; 
while  some  of  the  more  common  varieties  are  prepared  by 
mixing  lampblack  or  other  black  pigments  with  sufficient 
red  oxide  and  ochre  to  give  the  desired  shade. 

232.  Analyses  of  two  Vandyke-Browns  by  the  author 
gave  the  following  results. 

I.  II. 

Organic  matter  and  moisture     .    .  90.95  91.10 

Ash 9.05  8.90 

Silica 1.90  2.61 

Alumina  and  ferric  oxide    ...  1 . 43  1 . 50 

Calcium  carbonate 4 . 98  3 . 28 

Soluble  salts  ....  0 . 74  1.51 


100.00  100.00 

Analysis  of  Umbers  and  Siennas. 

233.  Hygroscopic  moisture.     Heat  2  grams  at  105°  C. 
for  3  hours.     Loss  in  weight  represents  hygroscopic  moist- 
ure. 

234.  Combined    water.     Transfer    above    sample    to    a 
weighed   platinum   crucible   and   heat  for  1  hour  over  an 
ordinary  lamp,  or  better  in  a  muffle.     Loss  in  weight  indi- 
cates amount  of  combined  water.     Carbonates  and  organic 
matter  render  the  results  inaccurate.     In  which  case  con- 
tinue the  ignition  at  bright  red  heat  for  several  hours,  and 
weigh  again.     Determine  the  carbon  dioxide  in  another 
portion  of  the  sample  and  estimate  the  combined  water 
by  difference. 

235.  Silica  and  barium  sulphate.     One  gram  of  the  pig- 
ment is  intimately  mixed  with  6  to  8  grams  of  potassium 


BLACK  AND  BROWN  PIGMENTS.  153 

bisulphate  and  fused  in  a  large  porcelain  crucible,  the  cover 
of  which  is  small  enough  to  set  inside  the  top  of  the  crucible, 
at  not  too  high  a  temperature  for  one-half  hour.  Finally 
heating  the  side  of  the  crucible  to  finish  the  conversion  of 
any  material  adhering  to  the  cover  and  upper  portion  of 
the  crucible.  The  iron,  manganese,  aluminum,  calcium,  and 
magnesium  are  converted  into  sulphates,  the  barytes 
remains  unchanged  and  the  silica  is  completely  dehydrated. 
After  cooling,  the  entire  contents  of  the  crucible  may  be 
shaken  loose  and  dissolved  in  sufficient  water  and  a  little 
hydrochloric  acid.  Filter  and  make  up  to  250  c.c. 

236.  The  residue  remaining  on  the  filter,  which  should 
be  white,  a  red  or  brownish  color  indicating  incomplete 
fusion  with  potassium  bisulphate,  in  which  case  the  sample 
must  be  fused  again,  is  ignited  and  weighed  in  a  platinum 
crucible.    The  residue  is  tested  for  barium  sulphate  by  the 
flame  test,  if  absent  the  residue  is  reported  as  silica;  if 
present  the  residue  is  treated  in  the  crucible  with  hydro- 
fluoric acid  until  a  thin  paste  is  formed.     The  mixture  is 
stirred  with  a  platinum  wire  and  digested  at  a  gentle  heat, 
finally  two  or  three  drops  of  sulphuric  acid  are  added,  and 
the  temperature  gradually  raised  until  no  further  loss  in 
weight  takes  place,  indicating  that  the  silica  has  been  com- 
pletely expelled.     The  residue  is  weighed  as  barium  sul- 
phate and  the  loss  in  weight  represents  the  silica. 

237.  Ferric  oxide.    An  aliquot  portion  of  the  solution 
from  235  is  heated  nearly  to  boiling  and  stannous  chloride 
solution  added  cautiously  until  the  yellow  color  has  disap- 
peared, and  then  a  slight  excess  added.    All  at  once  with 
vigorous  shaking  of  the  flask  50  c.c.  of  mercuric  chloride 
solution  is  added,  then  50  c.c.  of  the  manganous  sulphate 
solution.     Dilute  with  cold  fresh  boiled  water  and  titrate 
with    permanganate    solution.    Calculate    iron    found    to 
ferric  oxide. 


154  ANALYSIS  OF   MIXED   PAINTS. 

238.  Manganese.     Digest  0.5  grams  of  the  sample  with 
15  c.c.  of  concentrated  hydrochloric  acid  until  all  of  the 
iron  and  manganese  has  dissolved,  then  add  5  c.c.  of  sul- 
phuric acid  diluted  with  10  c.c.  of  water,  and  evaporate  on 
the  hot  plate  until  all  of  the  hydrochloric  acid  is  expelled 
as  shown  by  copious  evolution  of  sulphur  trioxide  fumes. 
Cool,  dissolve  in  about  25  c.c.  of  water,  and  heat  carefully 
with  occasional  shaking  until  all  of  the  anhydrous  sulphate 
of  iron  has  dissolved.     Transfer  to  a  250  c.c.  graduated 
flask  and  add  an  excess  of  zinc  oxide  emulsion,  obtained 
by  mixing  C.  P.  zinc  oxide  with  water.    Avoid  a  large 
excess,  but  sufficient  to  precipitate  all  the  iron,  so  that  on 
standing  the  solution  begins  to  settle  clear  and  some  zinc 
oxide  can  be  seen  in  the  bottom  of  the  flask.     Cool  and 
make  up  to  the  mark. 

239.  Transfer  an  aliquot  portion  to  a  beaker  or  flask,  and 
add  an  excess  of  a  saturated  solution  of  bromine  water  and 
about  3  grams  of  sodium  acetate.     One  c.c.  of  a  saturated 
solution  of  bromine  water  will  precipitate  about  0.01  gram 
of   manganese.     Boil   for   about   2   minutes.     Filter   and 
wash  with  hot  water.     The  filtrate  must  be  perfectly  clear. 
Place  the  filter  containing  the  washed  precipitate  back  in 
the  beaker  or  flask  in  which  the  precipitation  was   made. 
All  traces  of  bromine  must  be  entirely  expelled. 

240.  Add  an  excess  of  standard  oxalic  acid  solution  and 
about  50  c.c.  of  dilute  sulphuric  acid  (1:9)  and  heat  nearly 
to  boiling  with  gentle  agitation  until  the  precipitate  is 
entirely  dissolved.     Dilute   to   about   200   c.c.   with   hot 
water,  and  titrate  with  standard  permanganate. 

Standard  oxalic  acid  solution.  Dissolve  12.6048  grams 
of  chemically  pure  oxalic  acid  in  freshly  boiled  water  and 
make  to  1000  c.c.  in  a  graduated  flask. 

One  c.c.  of  this  solution  =  .0055  gram  of  manganese. 
The  oxalic  acid  solution  should  be  standardized  against 


BLACK  AND   BROWN  PIGMENTS.  155 

the  standard  permanganate  solution  and  the  correction 
factor  calculated. 

Example:  Wt.  of  sample  taken  =  0.5  gram. 
Volume   of   solution  =  250  c.c. 
Aliquot  portion  used  ==  100  c.c.  =  0.2  gram. 
1  c.c.  of  permanganate  sol.  =  0.499  c.c.  of  oxalic  acid. 
1    c.c.    of  oxalic  acid    sol.  =  0.0055  gram  of  manganese. 

Permanganate  solution  used  in  titrating  excess  of  oxalic 
acid  solution  =  13.2  c.c. 

13.2  c.c.  =  6.59  c.c.  of  oxalic  acid. 
Oxalic  acid  solution  used,  10.00  c.c. 

Excess,  6.59  c.c. 

Consumed,  3.41  c.c. 

3.41  X  .0055  =  .018755  g  Mn. 
Mn  :  Mn02  :  .018755  :  x. 
x  =  .02967  g.  MnOr 
.02967  -5-  0.2  -  14.84  per  cent  Mn02. 

241.  Alumina.  Fifty  c.c.  of  the  250  c.c.  solution  pre- 
pared in  235,  is  treated  with  about  20  grams  of  solid  ammo- 
nium chloride,  made  just  alkaline  with  ammonia,  heated, 
allowed  to  settle,  decanted,  filtered  and  washed.  The 
precipitate  is  dissolved  on  the  filter  with  hydrochloric  acid 
and  after  washing  with  small  portions  of  boiling  water,  the 
iron  and  aluminum  is  re  precipitated,  solid  ammonium 
chloride  being  added  as  before.  The  precipitate  is  washed 
by  decantation,  filtered  and  the  filtrate  collected  in  the 
beaker  containing  the  first  filtrate.  This  treatment  frees 
the  iron  and  aluminum  from  any  manganese  and  the 
precipitate  may  be  dried,  ignited  and  weighed  in  the  usual 
manner,  the  alumina  being  obtained  by  difference.  It  is 
often  advisable  to  make  another  reprecipitation  of  the  iron 
and  alumina,  using  but  a  small  amount  of  ammonium 
chloride. 


156  ANALYSIS  OP^  MIXED  PAINTS. 

242.  Calcium  and  magnesium.  The  combined  filtrates 
from  the  iron  and  alumina  are  treated  with  colorless 
ammonium  sulphide  in  such  a  manner  as  to  form  the  green 
sulphide  of  manganese  which  is  very  much  easier  to  filter 
than  the  pink  sulphide. 

The  colorless  ammonium  sulphide  may  be  prepared  as 
follows:  Saturate  one-half  of  a  solution  of  100  c.c.  of  water 
and  50  c.c.  of  ammonia  (sp.  gr.  0.90)  with  hydrogen  sul- 
phide, and  then  add  the  other  half  of  the  solution. 

For  the  precipitation  of  the  manganese,  25  c.c.  of  the 
ammonium  sulphide  solution  and  10  c.c.  of  ammonium 
chloride  solution  containing  3  grams  of  the  dry  salt,  are 
placed  in  a  50  c.c.  Erlenmeyer  flask,  the  solution  diluted 
to  about  100  c.c.  and  heated.  As  soon  as  it  comes  to  a 
boil,  the  combined  filtrate  from  the  iron  and  alumina  is 
added  and  the  beaker  rinsed  with  a  little  water.  The 
flask  is  shaken  vigorously  and  the  solution  kept  nearly 
at  the  boiling  point.  After  alternate  shaking  and  heating, 
the  pink  sulphide  of  manganese  turns  green  and  settles 
readily,  leaving  a  clear  supernatent  liquid.  If  the  ammo- 
nium sulphide  is  of  the  proper  strength  and  a  sufficient 
amount  be  used,  there  should  be  no  difficulty  in  obtaining 
the  green  sulphide  in  proper  condition  for  filtering. 

After  filtering  off  the  manganese,  the  filtrate  is  evapo- 
rated to  a  syrupy  consistency  and  20  c.c.  of  nitric  acid 
(sp.  gr.  1.2,)  added  in  small  portions,  evaporating  each 
time.  Sufficient  hydrochloric  acid  is  added  and  heat 
applied,  until  the  brown  fumes  cease  to  be  given  off.  This 
treatment  which  removes  the  excess  of  ammonium  salts 
is  not  necessary  if  magnesium  is  known  to  be  absent. 

The  solution  after  the  removal  of  the  nitric  acid 
is  diluted  with  water,  made  alkaline  with  ammonia  and 
the  calcium  and  magnesium,  separated  and  estimated  in 
the  usual  manner,  both  being  calculated  to  the  oxides. 


BLACK   AND   BROWN   PIGMENTS. 


157 


The  calcium  may  have  been -present  as  carbonate  or  sul- 
phate or  both.  Hence  an  estimation  of  the  combined 
sulphuric  acid  present  in  the  original  sample  is  necessary. 
For  this  purpose  1  gram  is  dissolved  in  30  c.c.  of  strong 
hydrochloric  boiled  10  minutes,  diluted  with  50  c.c.  of 
water  heated  to  boiling,  filtered,  and  washed  with  hot 
water.  Neutralize  the  filtrate  with  ammonia  then  make 
just  distinctly  acid  with  hydrochloric  acid,  boil,  add  10  c.c. 
of  barium  chloride  solution,  continue  boiling  for  10  min- 
utes, filter,  wash,  ignite  and  weigh  as  barium  sulphate. 
Calculate  combined  sulphuric  acid  by  multiplying  weight 
of  precipitate  by  0.343. 

Calculate  the  combined  sulphuric  acid  found  to  calcium 
sulphate  and  the  remaining  calcium  to  oxide. 

243.  ANALYSES  OF  UMBERS  AND  SIENNAS  BY  THE  AUTHOR. 

I.  II. 

Raw  Burnt 

Sienna.  Sienna. 

Moisture 0.42  0.44 

Loss  on  ignition 12.28  12.67 

Silica 36.85  19.55 

Ferric  oxide 45.18  62.75 

Alumina 3.00  1.66 

Calcium  oxide 1.09  2.52 

Magnesium  oxide 0 . 85  0 . 00 

Sulphur  trioxide 0.15  0.20 

Manganese  dioxide 0.13  0.17 

Undetermined 0.05  0.04 

100.00  100.00 

III.  IV. 

Raw  Burnt 

Umber  Umber. 

Moisture 1.78  2.01 

Loss  on  ignition 13.64  3.94 

Silica 20.60  24.21 

Ferric  oxide 42.60  51.04 

Alumina 2.90  6.80 

Calcium  oxide 3 . 68  1 . 95 

Magnesium  oxide 2.16 

Sulphur  trioxide 0.36  0.22 

Manganese  dioxide 11.95  9.79 

Undetermined 0.33  O.O4 

100.00  100. uu 


158  ANALYSIS  OF  MIXED  PAINTS. 

Analysis  of  Mixed  Paints  Containing  Umbers, 
Siennas  and  Ochres. 

244.  Determine  the  manganese  in  a  separate  sample  as 
determined  under  the  analysis  of  umbers.  Determine  the 
lead  as  in  white  paints,  using  the  filtrate  from  the  lead 
sulphide  for  the  estimating  of  the  iron,  which  must  be 
oxidized  by  boiling  with  a  little  nitric  acid  before  precipi- 
tating. Determine  aluminum,  zinc,  calcium,  and  mag- 
nesium as  described  under  analysis  of  umbers  and  siennas. 
The  zinc  being  precipitated  as  the  sulphide  after  the 
removal  of  the  iron,  and  aluminum,  is  contaminated  with 
manganese  sulphide.  Dissolve  the  mixed  sulphides  in  dilute 
hydrochloric  acid,  boil  until  odor  of  hydrogen  sulphide  is 
expelled.  Cool.  Add  excess  of  sodium  hydroxide  and 
filter  off  the  precipitated  manganese  hydroxide,  washing 
thoroughly.  The  filtrate  containing  the  zinc  in  solution  as 
sodium  zincate,  is  acidified  with  hydrochloric  acid,  heated 
to  about  80°  C.  and  titrated  with  potassium  ferrocyanide 
in  the  usual  manner. 

Any  barytes,  silica  and  insoluble  silicates  are  separated 
and  estimated  as  usual. 


CHAPTER  XIII. 

ANALYSIS  OF  BLUE  PIGMENTS  AND  PAINTS. 

Analysis  of  Prussian  Blues,  Chinese  Blues,  etc. 

245.  Hygroscopic    moisture.      Heat  2  grams  to  105°  C. 
for  3  hours.     Loss  in  weight  represents  hydroscopic  mois- 
ture. 

246.  Water  of  combination.     The  water  of  combination, 
so  called,  cannot  with  advantage  be  determined  directly, 
but  can  be  approximated  by  subtracting  the  total  per 
cent  of  constituents  determined  —  hygroscopic  moisture, 
cyanogen,  iron,  aluminum,  alkali  metal,  alkaline  sulphate 
and  inert  base,  if  any  -  -  from  100  per  cent. 

247.  Iron.     Ignite  one  gram  at  a  temperature  sufficient 
to  decompose  the  last  trace  of  the  blue,  but  not  so  high  as 
to  render  the  oxide  of  iron  difficult  of  solution.     Dissolve 
in  25  c.c.  of  hydrochloric  acid  and  25  c.c.  of  water  with 
aid  of  heat.     Filter,  making  up  nitrate  to  250  c.c.     Titrate 
50  c.c.  with  potassium  permanganate,  after  adding  stan- 
nous  chloride,  mercuric  chloride  and  manganous  sulphate 
solution  in  the  usual  manner.     Calculate  to  metallic  iron. 

248.  Aluminum.     Precipitate  the   iron   and   aluminum 
from  50  c.c.  of  the  iron  solution.     Filter,  ignite  and  weigh, 
estimating  the  alumina  by  difference.     It  probably  exists 
in  the  Prussian  blue  as  aluminum  ferrocyanide.      Calcu- 
late to  metallic  aluminum. 

249.  Calcium.    Calcium    compounds    are    very    rarely 
found  in  Prussian  blues.     If  the  Prussian  blue  is  precipi- 
tated on  barytes,  the  latter  is  liable  to  contain  a  small 

159 


160  ANALYSIS  OF  MIXED  PAINTS. 

amount  of  calcium  carbonate  as  an  impurity.  Treat  the 
nitrate  from  248  with  ammonium  oxalate.  Settle,  filter, 
ignite  and  weigh  as  calcium  oxide.  Calculate  to  calcium 
carbonate. 

250.  Alkali  metal  and  alkaline  salts.      The  filtrate  from 
249  is  evaporated  to  dryness  in  a  weighed  evaporating  dish, 
the  ammonium  salts  completely  volatized,  the  alkaline 
salts  weighed,   and  the  chlorine  therein  determined   by 
titration  with  standard  silver  nitrate  solution.     The  alkali 
metal,  is,  almost  without  exception,  entirely  sodium  or 
potassium  and  not  a  mixture  of  the  two,  and  may  be  iden- 
tified by  the  flame  test  using  a  small    fragment  of    the 
weighed  alkaline  salt.    The  sulphuric  acid  is  estimated, 
in  50  c.c.  of  the  solution  prepared  under  247,  by  precipita- 
tion with  barium  chloride,   in  the  usual  manner.    The 
amount   obtained    is   calculated   to    sodium   sulphate   or 
potassium  sulphate  as  the  case  may  be.    The  potassium 
or  sodium  chemically  combined  with  the  Prussian  blue  is 
calculated  from  the  amount  of  chlorine  found  and  reported 
as  metallic  sodium  or  potassium. 

251.  Cyanogen.     Estimate  the  nitrogen  in  1  gram  of  the 
sample  by  the  Kjeldahl-Gunning  method.     Multiply  the 
nitrogen  obtained  by  1.86  to  convert  it  into  cyanogen. 

252.  Barytes,   silica,   clay,   etc.     The   insoluble   portion 
remaining  on  the  filter  paper  in  247  is  ignited  and  weighed. 
Fuse  with  sodium  carbonate  and  estimate  the  barytes, 
silica,  alumina,  etc.,  as  described  under  analysis  of  white 
paints. 

253.  Calculations.    The  amount  of  Prussian  blue  may 
be  calculated  approximately  by  multiplying  the  iron  con- 
tent by  3.03  or  the  nitrogen  content  by  4.4.    These  factors 
are  not  exact  as  Prussian  blues  have  varying  compositions. 

A  Prussian  blue  to  be  considered  pure  should  contain 
at  least  20  per  cent  of  nitrogen  and  30  per  cent  of  iron 


ANALYSIS  OF  BLUE  PIGMENTS. 


161 


calculated  on  the  dry  matter  and  after  burning  should  be 
entirely  soluble  in  hydrochloric  acid.  A  dry  blue  should 
contain  less  than  7  per  cent  moisture  and  the  sulphuric 
acid  in  the  Kjeldahl  nitrogen  determination  should  not 
be  blackened  which  would  indicate  organic  adulteration. 


254.  ANALYSES  OF 

Moisture  (lost  at  100°  C.)    .    . 
Water  of  combination,  etc.     . 
Cyanogen   ......... 

Iron    ........... 

Aluminum      ........ 

Alkali  metal  (Na)     ..... 

Alkaline  sulphate     ... 


PURE" 

I. 

5.61 
15.46 
37.72 
29.48 

1.82 


PRUSSIAN   BLUES.1 


II. 

3.54 

18.18 

41.10 

32.16 

.52 


III. 

5.36 

6.22 

42.97 

34.27 


7.60   (K)  4.50    (K)7.72 


2.31 


3.46 


IV. 

5.45 
13.07 
37.90 
30.32 

3.17 
(K)2.25 

7.84 


100.00   100.00   100.00   100.00 


Moisture  (lost  at  100°  C.  )    . 

Water  of  combination,  etc. 

Cyanogen 

Iron 

Aluminum 

Alkali  metal  (Na) 

Alkaline  sulphate 


V. 

74  .  53 

3.08 

10.64 

7.97 

.72 


VI. 
5  .  32 

7.86 
39.91 
30.94 

1.00 


VII. 

5  .  56 
14.60 
40.19 
31.94 

1.43 


(K)1.06  (K)11.31  Na   2.52 


VIII. 

5.61 
16.93 
40.86 
31.25 

1.52 
.76 


2.00 


3.66 


3.76     Na  3.  07 


100.00       100.00  100.00  100.00 

255-  ANALYSES  OF  CHINESE   BLUES   BY  AUTHOR. 

I.  II.  III. 

.    .    .             2.49  3.45  2.04 

.    .    .           12.69  18.12  8.75 

.    .    .           45.78  36.51  46.09 

35.87  32.34  35.86 

Nal.'57  (K)4'.89  Nas'.SO 

.    .    .             1.50  3.61  3.35 

.    .    .             0.10  1.08  0.11 

100.00  100.00  100.00 


Moisture  (lost  at  100°  C.) 

Water  of  Combination,  etc 

Cyanogen 

Iron 

Aluminum 

Alkali  metal 

Alkaline  sulphate 

Silica. 


Analysis    of    Mixed    Paints    containing    Prussian    Blue, 

Chinese  Blue,  etc. 

256.  Weigh  1  gram  into  a  250  c.c.  beaker,  add  30  c.c. 
of  concentrated  hydrochloric  acid,  boil  5  minutes,  add  50 
1  Parry  and  Coste,  The  Analyst,  Vol.  XXI.,  page  227. 


162  ANALYSIS  OF  MIXED  PAINTS. 

c.c.  of  hot  water,  boil  10  minutes,  filter.  Wash  thoroughly 
with  boiling  water.  Ignite,  filter  and  precipitate  gently, 
so  as  to  destroy  the  blue  color  but  not  at  a  sufficiently  high 
temperature  to  render  the  iron  oxide  difficultly  soluble  in 
acid.  Cool  digest  in  moderately  concentrated  hydrochloric 
acid  until  the  iron  is  all  dissolved.  Dilute,  filter,  adding 
this  filtrate  to  the  first  filtrate.  The  insoluble  residue  is 
ignited,  weighed  and  fused  with  sodium  carbonate,  the 
barium,  silica  and  alumina  separated  as  described  under 
analysis  of  white  paints.  The  lead,  iron,  soluble  alumi- 
num, zinc  and  any  calcium  and  magnesium  compounds 
separated  and  estimated  as  described  under  analysis  of 
mixed  paints  containing  blacks  and  oxide  of  iron 
pigments. 

257.  If  the  paint  in  question  is  free  from  other  iron  pig- 
ments the  percentage  of  Prussian  blue  may  be  calculated 
by  multiplying  the  iron  content  by  3.03.     If  other  iron 
pigments  are  present  the  nitrogen  content  must  be  deter- 
mined; this  multiplied  by  4.4  will  give  the  approximate 
amount  of  Prussian  blue  present. 

Analysis  of  Ultramarine.  ' 

258.  Properties.     Ultramarine  is  a  compound  of  silica 
containing  alumina,  soda,  sulphur  and  combined  sulphuric 
acid.     It  has  been  often  stated  that  ultramarine  cannot 
be  mixed  with  white  lead,  because  of  the  sulphur  content 
of  the  ultramarine,  but  the  author  has  ascertained  that  a 
great  many  paint  manufacturers  use  it  in  tinting  mixed 
paints  where  the  percentage  of  white  lead  does  not  exceed 
that   of  the  zinc,  without  any  harmful  results    following. 
Ultramarines  that  are  to  be  used  in  the  manufacture  of 
paper  should  be  tested  for  their  power  of  resisting  the 
action  of  alum,  by  boiling  5  grams  in  a  5  per  cent  alum 


ANALYSIS  OF  BLUE  PIGMENTS.  163 

solution.    As    found    on    the    market   ultramarines   vary 
much  in  tint,  brilliance  and  coloring  power. 

259.  Moisture.     Heat  2  grams  at  1.05°  C.  for  3  hours, 
cool  and  weigh. 

260.  Silica.     Digest  1  gram  in  a  casserole  provided  with 
a  beaker  cover,  with  30  c.c.  of  concentrated  hydrochloric 
acid.     Evaporate  to  complete  dryness,  cool,  add  2  c.c.  of 
concentrated  hydrochloric  acid,  evaporate  to  dryness,  and 
heat  gently  for  15  minutes.     Take  up  in  100  c.c.  of  hot 
water  add  10  c.c.  of  hydrochloric  acid.     Filter,  ignite  and 
weigh  as  silica. 

261.  Alumina.    The  filtrate  from  the  silica  is  made  just 
sufficiently  alkaline  with  ammonia  to  precipitate  the  alu- 
minum, heat  gently,  filter,  ignite  and  weigh  as  alumina. 

262.  Sodium  oxide.    The  filtrate  from  the  alumina  is 
neutralized  with  sulphuric  acid  in  a  porcelain  evaporating 
dish,  evaporated  to  dryness,  the  residue  treated  with  a 
little  sulphuric  acid,  evaporated  to  dryness  again,  treated 
with  water,  evaporated  to  dryness,  and  ignited  at  low  red 
heat,  cooled  and  weighed. 

Wt.  sodium  sulphate  X  0.4366  =  wt.  of   sodium  oxide. 

263.  Total  sulphur.     Fuse  1  gram  in  a  large  crucible 
with  a  mixture  of  potassium  nitrate  and  potassium  chlorate 
for  about  half  an  hour.     Dissolve  the  fused  mass  in  dilute 
hydrochloric  acid  and  boil  the  solution  with  strong  nitric 
acid  for  half  an  hour,  filter  off  the  silica  and  precipitate 
the  sulphuric  acid  with  barium  chloride  in  the  usual  man- 
ner.    Filter,  ignite,  and  weigh  as  barium  sulphate. 

From  the  weight  of  barium  sulphate  thus  obtained 
deduct  the  weight  found  in  264,  the  difference  is  the  amount 
due  to  sulphur  present  in  the  blue  as  sulphide. 

Wt.  barium  sulphate  X  0.1373  =  wt.  sulphur. 

264.  Combined    sulphuric    acid.     Dissolve    1    gram    in 
dilute  hydrochloric  acid.     Filter  off  the  silica,  make  filtrate 


164  ANALYSIS  OF  MIXED  PAINTS. 

alkaline  with  ammonia  and  then  just  distinctly  acid  with 
hydrochloric  acid  and  treat  with  barium  chloride  in  the 
usual  manner.  The  precipitated  barium  sulphate  is  fil- 
tered, ignited,  and  weighed  as  usual. 

Wt.   barium    sulphate  X  0.3434  =  wt.   of  sulphur  tri- 
oxide. 

265.  ANALYSES  OF  ULTRAMARINES  BY  THE  AUTHOR. 

Ultra-  Ultra-  Ultra- 
marine marine  marine 
Blue.  Blue.          Blue. 
I.  II.  III. 

Silica 39.26  39.45  41.92 

Alumina 25.60  25.81  26.21 

Sulphur 11.69  12.02  10.82 

Sulphur  trioxide 3.10  2.33  1.93 

Sodium  oxide 19.87  19.73  18.40 

Water  0.48  0.66          0.72 


100.00       100.00       100.00 
266    ANALYSES  OF  ULTRAMARINES  BY  HURST. 


Silica  
Alumina     ~  . 
Sulphur              .            .    . 

Sulphate. 

49.69 
23.00 
9  23 

Soap 
Makers. 
40.65 
25.05 
12.95 

Calico 
Printers. 
40.89 
24.11 
13.74 

Paper 
Makers. 
45.42 
21.15 
11  62 

Sulphur  trioxide   .... 
Soda   
Water     

2.46 
12.49 
3.13 

4.81 
14.26 

2.28 

3.05 
15.61 
2.60 

5.58 
9.91 
6.32 

100.00   100.00   100.00   100.00 

Analysis  of  Cobalt  Blue. 

267.  This  pigment  which  is  essentially  a  compound  of 
the  oxides  of  alumina  and  cobalt  has  largely  gone  out  of 
use,  but  that  it  still  finds  a  limited  application  is  evidenced 
by  the  fact  that  the   author  receives  occasional  samples 
for  analysis.     Certain  shades  of  ultramarine  blue  are  often 
sold  under  the  name  of  cobalt  blue. 

268.  Moisture.     Determine  as  usual. 


ANALYSIS  OF  BLUE  PIGMENTS.  165 

269.  Alumina.     Fuse  1  gram  with  potassium  bisulphate 
as  described  under  analysis  of  Indian  reds  and  Venetian 
reds.     Dissolve  in  water  and  hydrochloric  acid,  filter  and 
make  up  to  250  c.c.  in  a  graduated  flask.     Any  residue 
remaining  on  the  filter  paper  is  ignited  and  weighed  as 
silica,  unless  barium  sulphate  is  present  which  would  be 
shown  by  the  flame  test. 

An  aliquot  portion  of  the  solution  is  treated  with  an 
excess  of  ammonium  chloride,  and  then  made  just  dis- 
tinctly alkaline  with  ammonia.  Filter,  dissolve  on  the 
filter  with  hydrochloric  acid  and  re  precipitate.  Filter 
again,  combining  the  two  filtrates.  Wash  thoroughly, 
ignite  and  weigh  as  alumina. 

270.  Calcium  and  magnesium.     The  combined  filtrates 
from  the  alumina  are  saturated  with  hydrogen  sulphide, 
filtered  and  any  calcium  and  magnesium  estimated  in  the 
filtrate  in  the  usual  manner. 

271.  Cobalt  oxides.    The  oxides  of  cobalt  present  are 
best  estimated  by  difference,  by  substracting  the  deter- 
mined constituents  from  100.     It  is  stated  by  Hurst  that 
phosphoric  acid  is  occasionally  used  in  the  manufacture  of 
cobalt  blues,  in  which  case  it  should  be  removed  before 
estimating  the  aluminum,  calcium  and  magnesium.    The 
several  samples  examined  by  the  author  were  found  to  be 
free  from  phosphoric  acid. 


CHAPTER  XIV. 

ANALYSIS   OF   YELLOW,    ORANGE,  AND   RED   CHROME 
LEADS,   ANALYSIS   OF   VERMILIONS. 

272.  Composition.    The  lemon  yellow  chromes  usually 
contain  sulphate  of  lead,  sometimes  carbonate  of  lead. 
The  red  chromes,  known  by  the  various  names  of  scarlet 
chrome,  chrome  red,  Chinese  red,    American  vermilion, 
and  vermilion  substitute  may  be  considered  as  basic  chro- 
mates  of  lead.     Often  these  basic  chromes  are  brightened 
up  by  having  precipitated  on  them  an  organic  color;  this 
may  be  tested  for  by  treating  a  portion  of  the  pigment 
with  alcohol,  which  will  dissolve  the  organic  color,  giving 
a  strongly  colored  solution.     See  analysis  of  vermilions. 

273.  Hygroscopic  moisture.     Heat  2  grams  at  105°  C. 
for  3  hours.     Loss  in  weight  represents  hygroscopic  mois- 
ture. 

274.  Barytes,  silica  and  clay.     One  gram  of  the  pigment 
is  boiled  for  5  minutes  with  30  c.c.  of  concentrated  hydro- 
chloric acid  in  a  covered  beaker.     While  boiling  add  half 
a  dozen  drops  of  alcohol  one  at  a  time.     Fifty  c.c.  of  water 
is  added  and  the  boiling  continued  for  10  or  15  minutes. 
Filter,   wash  thoroughly  with  boiling  water,   ignite  and 
weigh.    The  insoluble  residue  is  fused  with  sodium  car- 
bonate and  the  barium,  silica  and  alumina  separated  as 
described  under  analysis  of  white  paints. 

275.  Lead.    The  filtrate  from  the  insoluble  residue  is 
neutralized  with  dilute  ammonia  until  the  further  addition 
of  another  drop  would  cause  the  formation  of  a  permanent 

166 


ANALYSIS  OF  LEADS.  167 

precipitate,  diluted  to  about  250  c.c.  to  300  c.c.,  and  hydro- 
gen sulphide  passed  in  for  10  minutes. 

Solutions  containing  large  amounts  of  chromium  if 
neutralized  with  ammonia  until  a  permanent  precipi- 
tate appears,  seem  to  require  an  excess  of  hydrochloric 
acid  for  their  resolution,  sufficient  to  prevent  the  satis- 
factory precipitation  of  the  lead  with  the  hydrogen 
sulphide. 

Allow  the  precipitate  to  settle  thoroughly  as  it  renders 
the  filtering  much  easier,  filter,  wash  with  hydrogen  sul- 
phide water.  Boil,  filter,  and  precipitate  with  dilute  nitric 
acid,  until  all  of  the  lead  has  .dissolved,  filter  with  aid  of 
suction,  washing  thoroughly  with  hot  water.  Add  5  c.c. 
of  concentrated  sulphuric  acid,  diluted  with  an  equal 
volume  of  water  to  the  filtrate.  Evaporate  on  hot  plate 
until  the  white  fumes  of  sulphur  trioxide  appear.  Cool, 
dilute  with  water,  add  an  equal  volume  of  alcohol,  filter, 
washing  with  dilute  alcohol,  ignite  gently,  and  weigh  as 
lead  sulphate.  Save  filtrate. 

276.  Chromium.  The  alcoholic  filtrate  from  the  lead 
sulphate  is  evaporated  nearly  to  dryness  to  expel  alcohol, 
and  the  filtrate  from  the  lead  sulphide  heated  until  the 
hydrogen  sulphide  is  expelled.  The  two  filtrates  are 
mixed,  diluted  if  necessary,  and  made  just  perceptibly 
alkaline  with  ammonia;  boil,  settle,  filter,  wash  thoroughly, 
ignite  and  weigh  as  chromic  oxide. 

Wt.  chromic  oxide  X  1.3137  =  wt.  chromic   anhydride. 

Occasionally  these  pigments  contain  a  small  quantity  of 
iron,  which  should  be  tested  for  qualitatively  in  a  separate 
portion  of  the  pigment.  If  found  to  be  present  the  precipi- 
tate of  ferric  and  chromium  hydroxides  is  dissolved  on  the 
filter  with  hydrochloric  acid,  the  filter  washed  thoroughly 
with  hot  water,  and  the  iron  and  chromium  in  the  filtrate 
reprecipitated  with  ammonia  and  treated  with  sodium 


168  ANALYSIS  OF  MIXED  PAINTS. 

peroxide  to  dissolve  the  chromium  as  described  under  the 
analysis  of  chrome  greens. 

277.  Calcium.     The    filtrate    from    the    chromium    is 
treated  with  ammonium  oxalate,  allowed  to  stand  in  a 
warm  place  for  an  hour  or  so,  filtered,  washed  thoroughly, 
strongly  ignited  and  weighed  as  calcium  oxide. 

278.  Magnesium.     The  magnesium  is  estimated  in  the 
filtrate  from  the  calcium  in  the  usual  manner. 

279.  Combined  sulphuric  acid.    The  combined  sulphuric 
acid  may  be  estimated  by  either  of  the  two  methods  given 
in  paragraph  170,  analysis  of  white  paints.     In  fact,  the 
latter  method  may  be    used    for  the   rapid  analysis  of  a 
chrome  lead,  the  insoluble  lead  carbonate  being  filtered  off, 
the  chromium  precipitated  as  the  hydroxide  in  the  usual 
manner,  and  the  combined    sulphuric  acid  estimated    in 
the  filtrate  from  the  chromium. 

Wt.  barium  sulphate  X  0.3433  =  combined  sulphuric 
acid. 

280.  Calculations.     If  calcium  is  absent,  or  present  as 
carbonate,  the  combined    sulphuric    acid  is  calculated  to 
lead  sulphate,  the  chromic  anhydride  to  lead  chromate, 
and  excess  of  lead  to  lead  oxide.     If  calcium  sulphate  and 
carbonate  of  lead  are  present,  the  carbon  dioxide  must  be 
determined  and  the  amount  of  calcium  present  as  sulphate 
estimated   by  Thompson's    method    as    described   under 
analysis  of  white  paints. 

Wt.  comb,  sulphuric  acid  X  3.788  =  wt.  lead  sulphate. 

Wt.  chromic  anhydride  X  3.230  =  wt.  lead  chromate. 

Wt.  lead  chromate  X  0.6406  =  wt.  lead. 

Wt.  lead  X  1.0773  =  wt.  lead  oxide. 

The  specifications  for  chrome  leads  issued  by  the  U.  S. 
Treasury  Department,  1907,  state  that  a  color  containing 
lead  sulphate  is  to  be  preferred  to  one  containing  white 
lead. 


ANALYSIS  OF  LEADS.  169 

281.   ANALYSES  OF  CHROME   LEADS   BY  AUTHOR. 

Light  Deep 

Chrome  Orange 

Yellow.  Chrome 
Yellow. 

Moisture 0.04  0.03 

Lead  chromate 68.65  40.56 

Lead  oxide 47.24 

Lead  sulphate 31.21  5.49 

Silica ...  0 . 74 

Alumina ...  0.44 

Organic  color ...  4 . 87 

Undetermined 0.10  0.63 

100.00       100.00 

Analysis  of  Mixed  Paints  Containing  Chrome  Yellows  and 

Ochres. 

282.  Barytes,  silica  and  clay  are  estimated  as  described 
under  analysis  of  chrome  leads. 

283.  Lead,  both  as  sulphate  and  carbonate,  is  estimated 
as  described  under  chrome  leads,  the  filtrate  from  the  lead 
sulphate  being  saved  as  before. 

284.  Iron.    The  filtrate  from  the  lead  sulphide  is  heated 
until  all  o'f  the  hydrogen  sulphide  has  been  expelled  and 
added  to  the  filtrate,  from  the  lead  sulphate,  from  which 
the  alcohol  has  been  expelled  by  boiling.     A  few  drops  of 
nitric  acid  are  added  and  the  solution  boiled  for  a  minute 
or  two,  then  made  just  distinctly  alkaline  with  ammonia, 
boiled,  settled  and  filtered. 

Dissolve  on  the  filter  with  hot  dilute  hydrochloric  acid, 
wash  with  hot  water.  Cool.  Reprecipitate  with  ammo- 
nia, avoiding  excess,  without  waiting  for  the  precipitate 
to  settle,  carefully  add  a  sufficient  quantity  of  sodium 
peroxide  (1  gram  is  usually  sufficient)  keeping  the  beaker 
covered  meanwhile.  Digest  until  all  of  the  chromium  and 
aluminum  have  passed  into  solution,  adding  more  peroxide 
if  necessary.  The  iron  remains  undissolved  while  the 
chromium  and  aluminum  go  into  solution,  filter,  wash 


170  ANALYSIS  OF  MIXED  PAINTS. 

thoroughly,  ignite  strongly  and  weigh  as  ferric  oxide, 
or  dissolve  in  dilute  hydrochloric  acid  and  titrate. 
The  treatment  with  peroxide  is  preferably  performed  in  a 
porcelain  evaporating  dish. 

285.  Chromium.     The  filtrate  from  the  iron  is  made  up 
to  250  c.c.  in  a  graduated  flask.     An  aliquot  portion  is 
rendered  acid  with  acetic  acid  and  a  slight  excess  of  lead 
nitrate  solution  added,  allowed  to  remain  on  the  hot  plate 
until  thoroughly  settled,  filtered  on  to  a  weighed  Gooch 
crucible,  washed,  dried  and  weighed  as  lead  chromate. 

286.  Aluminum.     An  aliquot   portion   of  the  250  c.c. 
solution  is  made  just  acid  with  hydrochloric  acid,  and  then 
just  distinctly  alkaline  with  ammonia,  allowed  to  settle, 
filtered  on  to  a  Gooch  crucible,  ignited  and  weighed  as 
alumina. 

287.  Zinc.    The  filtrate  from  the  chromium,  iron  and 
aluminum  hydroxides,  under  iron  is  mixed  with  the  filtrate 
from  the  lead  sulphate  from  which  the  alcohol  has  been 
expelled,  and  the  mixed  solution  saturated  thoroughly  with 
hydrogen  sulphide,  boiled  with  the  addition  of  solid  ammo- 
nium chloride  to  render  the  precipitate  less  slimy,  and 
filtered.    The  zinc  sulphide  dissolved   with  hydrochloric 
acid,  boiled  to  expel  hydrogen  sulphide  and  titrated  with 
standard   ferrocyanide  of   potassium    as    described  under 
analysis  of  white  paints. 

288.  Calcium,  magnesium  and  combined  sulphuric  acid 
are  estimated  as  described  under  analysis  of  Chrome  Leads 
and  the  calculations  made  as  there  described. 

Analysis  of  Vermilion. 

289.  Properties.     Vermilion  is  a  bluish  scarlet  powder, 
having  a  specific  gravity  of  8.2.     It  is  insoluble  in  any 
single  acid  such  as  hydrochloric  or  nitric  acid  and  in  the 
alkalies.     Heated  in  contact  with  the  air  it  burns  with  a 


ANALYSIS  OF  LEADS.  171 

pale  blue  lambent  flame.  Pure  vermilion  will  burn  away 
entirely  or  at  least  leave  but  a  small  fraction  of  1  per  cent 
of  ash.  This  is  a  reliable  test  for  it,  as  other  adulterants 
would  be  left  behind  on  heating. 

The  most  common  adulterants  of  vermilion  are  red 
lead,  oxide  of  iron,  lead  chromes,  vermilionette  lakes, 
para  reds,  and  alizarine  reds. 

290.  Detection    of    vermilionettes,    para    and    alizarine 
reds.    (a).  Boil  a  little  of  the  dry  color  with  water,  settle 
and  filter.     Vermilionettes  give  a  deep  red  solution,  para 
reds  a  pale  brownish  or  orange,  and  the  alizarine  reds  a 
colorless  solution. 

(6).  Boil  a  little  of  the  dry  color  with  a  mixture  of 
methyl  and  ethyl  alcohol,  filter,  heat  and  settle.  Vermil- 
ionettes give  a  bright  red  solution,  usually  having  a  yellow 
bloom,  para  reds  an  orange  red  solution,  alizarine  reds  a 
practically  colorless  solution. 

(c).  Boil  another  portion  of  the  dry  pigment  with  some 
freshly  distilled  aniline,  settle,  and  filter.  Vermilionettes 
give  a  purple-red,  alizarine  lakes  a  pale  browrn,  and  the 
para  reds  an  intense  orange-red  solution. 

(d).  Boil  some  of  the  dry  color  with  a  solution  of 
caustic  soda.  Vermilionettes  give  a  red  solution  with 
a  green  "  bloom,"  para  reds  a  bluish-red  solution, 
while  alizarine  reds  yield  a  characteristic  deep  violet 
solution. 

291.  Barytes,  silica  and  clay.     Dissolve  1  gram  in  30  c.c. 
of  concentrated  hydrochloric  acid,  50  c.c.  of  water  with 
the  aid  of  1  to  2  grams  of  potassium  chlorate  added  in 
small  portions  and  warming.     Evaporate  to  dryness  on 
water-bath.    Take  up  in  50  c.c.  of  water  acidulated  with 
hydrochloric  acid,  heat  to  boiling  to  dissolve  any  lead 
chloride,  filter,  wash  with  boiling  water,  ignite  and  weigh 
any  insoluble  residue.     Fuse  with  sodium  carbonate  and 


172 


ANALYSIS  OF  MIXED  PAINTS. 


estimate    the    barium    sulphate,  silica    and    alumina  as 
described  under  analysis  of  white  paints. 

292.  Lead.     If    lead    is    present,    calcium    compounds 
being  absent,  the  nitrate  is  treated  with  sulphuric  acid, 
evaporated  carefully  to  expel  excess  of  hydrochloric  acid, 
diluted  with  water  and  alcohol,  the  lead  sulphate  filtered 
off  on  a  Gooch  crucible  in  the  usual  manner. 

293.  Mercuric  sulphide   (vermilion).      The  filtrate  from 
the  insoluble  residue,  if  lead  is  absent,  or  the  filtrate  from 
the  lead  sulphate,  is  heated  with  a  little  sulphurous  acid 
to  reduce  any  iron  present  to  the  ferrous  condition,  made 
neutral  with  ammonia,  and  then  fust  acid  to  litmus  with 
hydrochloric  acid. 

The  solution  is  diluted  to  about  350  c.c.  and  hydrogen 
sulphide  passed  in  for  10  minutes.  The  mercuric  sulphide 
is  filtered  off  on  a  weighed  Gooch  crucible,  washed  with 


FIG.  11. 

hydrogen  sulphide  water,  the  crucible  removed  to  another 
holder  and  washed  with  alcohol  and  carbon  bisulphide  to 
remove  sulphur,  dried  in  steam-oven  and  weighed. 

294.  Estimation  of  lead  and  mercury,  calcium  com- 
pounds present.  The  filtrate  from  the  insoluble  residue 
from  291  is  precipitated  with  hydrogen  sulphide  as  de- 


ANALYSIS  OF  LEADS.  173 

scribed  under  293,  collected  on  a  weighed  filter  and  dried 
at  100°  C.,  weighed  and  mixed  uniformly. 

An  aliquot  part  is  introduced  into  the  bulb  of  Fig.  11. 
A  slow  stream  of  washed  chlorine  gas  passed  through  it, 
and  a  gentle  heat  applied  to  the  bulb,  increasing  this 
gradually  to  faint  redness.  The  escaping  chlorine  is 
conducted  into  a  flue.  First,  sulphur  chloride  distils 
over,  which  decomposes  with  the  water  in  E  and  F.  The 
mercuric  chloride  formed  volatilizes,  condensing  partly 
in  E,  partly  in  0.  Cut  off  that  part  of  the  tube,  rinse 
the  mercuric  chloride  into  E  and  mix  the  contents  of 
the  latter  with  the  water  in  F.  Mix  the  solution  with 
excess  of  ammonia  and  warm  gently  until  no  more 
nitrogen  is  evolved,  acidify  with  hydrochloric  acid,  fil- 
ter and  determine  the  mercury  in  the  filtrate  as  under 
293. 

295.  Ferric  oxide.     The  filtrate  from  the  sulphides  is 
heated  until  all  of  the  hydrogen  sulphide  has  been  expelled 
and   the   iron  chromium  and   alumina   precipitated   with 
ammonia,  filtered  and  separated  as  described  under  analy- 
sis of  chrome  greens. 

296.  Zinc  oxide.    The  filtrate  from  the  iron  and  alu- 
mina precipitate  is  made  distinctly  alkaline  with  ammonia 
and  the  zinc  precipitated  with  hydrogen  sulphide.     The 
liquid  containing  the  zinc  sulphide  precipitate  is  heated 
to  boiling,  and  about  5  grams  of  solid  ammonium  chloride 
added,  which  renders  the  precipitate  easier  to  filter.     Settle 
filter,  wash  thoroughly.     Pierce  filter,  wash  through  into 
a  clean  beaker  with  water,  dissolving  the  residue  on  filter 
with  dilute  hydrochloric  acid,  and  washing  with  hot  water. 
Dilute,  heat  to  expel  hydrogen  sulphide  and  titrate  with 
ferrocyanide  as  previously  described.     If  iron  is  absent 
in  the  paint,  the  zinc  may  be  estimated  directly  as  described 
under  analysis  of  white  pigments. 


174 


ANALYSIS  OF  MIXED   PAINTS. 


297.  Calcium  and  magnesium.     Estimated  as  usual  in 
the  filtrate  from  the  zinc  sulphide. 

298.  Calculations.     If  chromium  is  present  it  is  calcu- 
lated to  basic  lead  chromate,  and  any  excess  of  lead  above 
that  required  to  form  the  chromate  is  calculated  to  red 
lead. 


299.  ANALYSES  OF  VERMILIONS  BY  THE  AUTHOR. 

I.                II.  III. 

English        English  Vermilion. 
Vermilion    Vermilion. 

Deep.  Pale. 

Sulphide  of  Mercury    ....       99.53         99.61  99.61 

Ash 0.47          0.39  0.39 

100.00       100.00  100.00 

I.  II. 

Vermilion.  Radium 
Vermilion. 

Moisture 0.16  0.06 

Red  lead 80.08  97.99 

Barytes      16.83 

Alumina 0 . 77 

Organic  color 2.16  1.95 

100.00  100.00 

I.  II. 

Light  Deep 

Vermilion.  Vermilion. 

Moisture 1.33  0.15 

Lead  chromate 50.16  53.60 

Lead  oxide 41.20  40.88 

Lead  sulphate 6.15  4.97 

Ferric  oxide 0 . 37  0 . 33 

Soluble  salts 0 . 33  trace 

Undetermined  .                                                     0.46  0.07 


100.00       100.00 

300.  Antimony  vermilion  and  orange.  These  two  pig- 
ments have  the  same  composition,  corresponding  to  the 
formula  of  antimony  trisulphide.  They  are  insoluble  in 
dilute  acids,  but  soluble  in  strong  hydrochloric  acid.  It 
is  seldom  necessary  to  make  a  complete  analysis  of  these 


ANALYSIS  OF  LEADS.  175 

pigments.  Adulteration  will  be  indicated  by  the  pigment 
not  being  completely  soluble  in  strong  hydrochloric, 
though  a  trace  of  sulphur  may  remain  undissolved,  floating 
on  top  of  the  acid. 

3ooa.     Analysis   of    Red   Lead.1      Solutions    required  : 

Ti 

—  iodine  solution,  stannous   chloride  solution  (14.1  g.  in 

1000  c.c.),  starch  paste  solution.  Pipette  25  c.c.  of  the 
stannous  chloride  solution  into  an  .Erlenmeyer  flask,  add 
40  c.c.  hydrochloric  acid,  boil  one  minute,  add  100  c.c. 
cold  water,  cool  rapidly  and  titrate  with  the  iodine 
solution,  using  starch  paste  as  an  indicator. 

Weigh  1  gram  of  the  sample  red  lead  into  a  similar 
Erlenmeyer  flask,  moisten  with  water,  add  25  c.c.  stan- 
nous chloride  and  40  c.c.  of  hydrochloric  acid,  boil  until  all 
of  the  lead  is  in  solution,  and  titrate  with  iodine  solution 
as  above.  The  difference  in  c.c.  of  iodine  solution  u^ed 
in  the  blank  and  in  the  determination  give  the  number  of 
c.c.  of  iodine  solution  to  which  the  available  oxygen  in 
the  red  lead  is  equivalent. 

1    c.c.  •—  iodine  sol.  =  0.8  m.g.  oxygen. 
Available  oxygen  X  42.73  =  amount  of  red  lead. 

1  J.  H.  Wainwright,  Engineering  Chemistry. 


CHAPTER  XV. 

ANALYSIS  OF  CHROME  GREENS  AND  EMERALD  GREENS. 

Analysis  of  Chrome  Greens. 

301.  Hygroscopic    moisture.     Heat    2    grams    of    the 
sample  at  105°  C.  for  3  hours.     Cool  and  weigh. 

302.  Organic    color.     Occasionally    chrome    greens    are 
brightened  up  by  treatment  with  an  organic  color.     Boil 
a  portion  of  the  sample  with  alcohol ;  a  green  colored  solu- 
tion not  due  to  suspended  particles  indicates  the  addition 
of  an  organic  color. 

303.  Barytes,    silica,    clay,    or  other   silicates.      Weigh 
1  gram  into  a  porcelain  crucible,  heat   gently,  so  as  to 
destroy  the  Prussian  blue,  but  not  at  a  temperature  suffi- 
ciently high  to  fuse  the  lead  chromate  or  render  the  iron 
difficultly  soluble  in  acid.     Cool.     Boil  gently  with  30  c.c. 
of  concentrated   hydrochloric   acid   in   a  covered  beaker 
until  all  of  the  iron  and  lead  have  gone  into  solution.     A 
few  drops  of  alcohol  added  one  at  a  time  may  assist  the 
solution.    Add  50  c.c.  water;  boil  for  15  minutes.     Filter 
hot,  wash  thoroughly  with  boiling  water,  ignite  and  weigh. 
Fuse  with  sodium  carbonate  and  estimate  the  barytes, 
silica  and  alumina  as  described  under  analysis  of  white 
paints. 

304.  Lead.    The  filtrate  from  the  barytes,  silica  and 
alumina  is  made  just  alkaline  with  ammonia,  and  then 
just  acid  to  litmus,  with  hydrochloric  acid ;  dilute  to  about 
300  c.c.  and  pass  in  a  current  of  hydrogen  sulphide  for 
10  minutes.    Allow  the  precipitate  to  settle  thoroughly. 

176 


ANALYSIS  OF  GREEN  PIGMENTS.  177 

Filter,  wash  with  hydrogen  sulphide  water.  Digest  pre- 
cipitate and  filter  in  a  covered  beaker  with  dilute  nitric 
acid  until  the  lead  is  entirely  dissolved,  filter  on  suction 
funnel,  wash  with  hot  water.  Add  5  c.c.  of  concentrated 
sulphuric  acid  diluted  with  an  equal  volume  of  water 
to  the  filtrate;  evaporate  on  sand  bath  until  white  fumes 
of  sulphur  trioxide  appear.  Cool,  dilute  with  50  c.c.  of 
water,  add  75  c.c.  of  alcohol  and  allow  to  stand  for  up- 
wards of  an  hour  with  occasional  stirring.  Filter  on  to 
Gooch  crucible,  washing  with  water  containing  2  per  cent 
sulphuric  acid,  finishing  with  50  per  cent  alcohol;  dry, 
heat  gently,  and  weigh  as  lead  sulphate.  Reserve,  filtrate. 

305.  Iron.    The  filtrate  from  the  lead  sulphide  is  heated 
to  expel  the  hydrogen  sulphide  and  added  to  the  filtrate 
from  the  lead  sulphate,  which  has  been  boiled  until  all 
of  the  alcohol  has  been  expelled.     A  few  drops  of  nitric 
acid  are  added,  the  solution  boiled  for  a  minute  or  two 
and  then   made  just  distinctly  alkaline  with  ammonia, 
filtered    and    washed.     Dissolve    on    the    filter    with    hot 
dilute  hydrochloric  acid,  wash  with  hot  water,  cool.    Re- 
precipitate  with  ammonia,  avoiding  excess,  without  wait- 
ing for  the  precipitate  to  settle;  carefully  add  a  sufficient 
quantity  of  sodium  peroxide  (1  gram  is  usually  sufficient) 
keeping  the  beaker  covered  meanwhile.     Digest  until  all 
of  the  chromium  and  aluminium  have  passed  into  solu- 
tion,   adding    more    peroxide    if    necessary.    The    ferric 
hydroxide  remains  undissolved  and  is  filtered  off,  washed 
thoroughly,  ignited,  and  weighed  as  ferric  oxide. 

306.  Chromium.     The  filtrate  from  the  ferric  hydroxide 
is  made  up  to  250  c.c.  in  a  graduated  flask,  and  an  aliquot 
portion  is  rendered  acid  with  acetic  acid,  a  slight  excess 
of  lead  nitrate  added,  and  heated  on  the  hot  plate  until 
the   precipitate   has   thoroughly   settled.     Filter  on  to  a 
weighed  Gooch  crucible,  dry,  and  weigh  as  lead  chromate, 


178  ANALYSIS  OF  MIXED  PAINTS. 

or,  the  precipitate  may  be  heated  gently  over  an  ordinary 
flame,  so  as  not  to  fuse  the  chromate. 

307.  Aluminium.     An  aliquot  portion  of  the  250  c.c. 
solution  is  made  just  acid  with  hydrochloric  acid,  and 
then  just  distinctly  alkaline  with  ammonia.     The  precipi- 
tate of  aluminium  hydroxide  allowed  to  settle,  filtered, 
ignited  and  weighed  as  alumina. 

308.  Calcium    and    magnesium    are    estimated    in   the 
filtrate  from  the  iron,  aluminium  and  chromium  hydrox- 
ides as  usual. 

309.  Cyanogen.     One  gram  of  the  sample  is  digested 
with  sulphuric  acid  and  the  nitrogen  estimated  as  under 
analysis  of  Prussian  blues. 

Wt.  nitrogen  X  1.86  =  wt.  Cyanogen. 

310.  Combined  sulphuric  acid.     Heat  gently  1  gram  of 
the  pigment  so  as  to  destroy  the  Prussian  blue,  dissolve 
in  30  c.c.  of  strong  hydrochloric  acid  in  a  covered  beaker. 
Dilute  with  50  c.c.  boiling  water,  boil  5  minutes,  filter, 
make  nitrate  neutral  with  ammonia,  then  slightly  acid 
with  hydrochloric  acid,  bring  to  boiling,  add  15  c.c.  barium 
chloride,   boil   10  minutes,   filter,   wash  with  hot  water, 
ignite,  and  weigh, 

Wt.  barium  sulphate  X  0.3433  =  combined  sulphuric  acid. 

311.  Calculations.    The  amount  of  Prussian  blue  present 
may  be  calculated,  either  by  multiplying  the  iron  content 
by  3.03  or  the  nitrogen  content  by  4.4.     The  chromium  is 
calculated  to  lead  chromate  and  the  combined  sulphuric 
acid,  in  the  absence  of  calcium  sulphate,  to  lead  sulphate 
excess  of  lea-d  over  that  required  for  the  lead  chromate  and 
lead  sulphate,  calculated  to  lead  oxide,  unless  the  basic  car- 
bonate of  lead  were  present,  which  is  very  rarely  the  case. 

NOTE.  In  making  an  analysis  of  a  mixed  paint  tinted  with  a  green, 
it  should  be  borne  in  mind  that  the  Prussian  blue  is  occasionally 
replaced  with  an  ultramarine  blue. 


ANALYSIS  OF  GREEN  PIGMENTS. 


179 


312.   ANALYSES   OF  CHROME   GREENS   BY   THE 
AUTHOR. 


I. 

II. 

Light 

Medium 

Chrome 

Chrome. 

Green. 

Green. 

Moisture     

0.20 

0.10 

Lead  chromate      

16.57 

16.67 

Lead  sulphate   
Prussian  blue 

5.80 
5  98 

5.29 
6.80 

Barytes 

68  .  22 

66.72 

Alumina 

1.40 

1.94 

Silica 

1.71 

1.66 

Undetermined 

0.12 

0.82 

100.00 

100.00 

Emerald  Green,  Paris  Green  and  Arsenic  Insecticides. 

313.  Properties.     The  chief  use  of  emerald  green,  better 
known  as  Paris  green,  is  as  an  insecticide,  but  little  being 
used  as  a  paint  pigment  owing  to  its  poisonous  qualities. 
As  a  pigment  it  is  very  opaque,  has  good  covering  power 
and    is    fairly    permanent.     It    is    completely   soluble    in 
ammonia,  turning  it  to  an  intense  blue  color.    This  test, 
however,   is  not   conclusive,   since   white   arsenic   and   a 
number  of  other  substances  used  in  adulterating  Paris 
green  are  soluble  in  ammonia  and  would  escape  detection 
if  this  method  alone  were  depended  on. 

Under  the  terms  of  the  North  Dakota  law  regulating 
the  sale  of  Paris  green  it  shall  be  deemed  adulterated  if 
it  contains  less  than  50  per  cent  of  total  arsenious  oxide, 
or  more  than  4  per  cent  of  free  or  uncombined  arsenious 
oxide.  In  most  cases  the  determination  of  water  soluble 
and  total  arsenious  oxides  is  sufficient. 

314.  Water  soluble  arsenious  oxide.     One-half  gram  of 
the  sample  is  weighed  into  a  250   c.c.    Erlenmeyer  flask, 


180  ANALYSIS  OF  MIXED  PAINTS. 

100  c.c.  of  distilled  water  added.  The  flask  is  agitated 
by  shaking  every  few  minutes  during  a  working  period  of 
8  hours,  keeping  the  temperature  between  25°  to  30°  C. 
The  next  day,  after  pouring  off  the  clear  liquid,  100  c.c. 
of  distilled  water  is  again  added,  and  the  shaking  treat- 
ment repeated.  The  clear  solution  is  again  poured  off, 
and  the  operation  repeated  with  a  fresh  portion  of  100  c.c. 
of  distilled  water.  The  three  100  c.c.  leachings  are  com- 
bined and  filtered  through  a  double  filter  and  titrated 
with  tenth-normal  iodine,  using  starch  as  an  indicator 
as  follows: 

Add  20  c.c.  of  a  saturated  solution  of  sodium  bicar- 
bonate to  every  0.1  gram  of  arsenious  oxide  and  titrate 
as  usual. 

1  c.c.  tenth-normal  iodine  =  0.00495  arsenious  oxide. 

3 15.  Total  arsenious  oxide.  Weigh  1  gram  of  the  sample 
into  a  side-neck  distilling  flask,  and  add  5  grams  of  ferrous 
sulphate.  Connect  with  a  condenser,  the  other  end  of 
which  dips  below  the  surface  of  about  100  c.c.  of  distilled 
water,  which  is  kept  cooled.  Fifty  c.c.  of  hydrochloric 
acid  are  added  to  the  flask  containing  the  sample,  which 
also  has  a  glass  tube  leading  nearly  to  the  bottom,  the 
other  end  of  which  is  connected  with  a  flask,  in  which 
hydrochloric  acid  gas  is  generated.  This  gas  is  very 
readily  obtained  by  allowing  concentrated  sulphuric  acid 
to  drop  into  concentrated  hydrochloric  acid  saturated 
with  sodium  chloride.  The  flask  containing  the  arsenic 
solution  is  cooled  nearly  to  zero,  by  immersing  the  flask 
into  a  vessel  containing  cracked  ice.  Pass  in  the  hydro- 
chloric acid  gas;  when  no  more  is  absorbed,  the  ice  is 
removed  and  the  solution  brought  to  a  boil.  The  stream 
of  hydrochloric  acid  gas  is  allowed  to  flow  and  the  distil- 
lation continued  until  the  volume  of  the  solution  is  reduced 
to  about  25  c.c.  The  distillate  is  just  neutralized  with  a 


ANALYSIS  OF  GREEN   PIGMENTS. 


181 


solution  of  sodium  hydroxide  or  sodium  carbonate,  a 
sufficient  amount  of  sodium  bicarbonate  added,  the  whole 
solution  made  to  a  definite  volume  and  an  aliquot  part 
titrated  with  tenth-normal  iodine  and  starch. 

316.   ANALYSES  OF  PARIS  GREENS,   BY   E.    F.   LADD. 


Laboratory  Number. 

Free 
Arsenious 
Oxide. 

Total 
Arsenious 
Oxide. 

101   .. 

3  46 

52  38 

102  .... 

7  41 

54  36 

103   

1  73 

45  46 

104   

6  17 

57  32 

105  

1  98 

57  32 

106  

1  48 

56  34 

107  

7  41 

59  72 

108  

18  77 

51  39 

109 

5  93 

52  18 

110 

98 

50  01 

111 

3  70 

An  inspection  of  the  above  shows  that  five  of  the  samples 
contained  excessive  amounts  of  free  arsenious  oxide 
ranging  from  9.93  to  18.77  per  cent,  while  one  of  the 
samples  contained  a  total  of  45.46  per  cent  of  arsenious 
oxide  instead  of  50  per  cent  prescribed  as  a  minimum. 

If  a  complete  analysis  is  desired,  the  following  scheme 
may  be  used. 

317.  Moisture.    Heat  2  grams  at  105°  C.  for  2  hours, 
cool  and  weigh. 

318.  Aniline  color.    Treat  a  portion  of  the  sample  with 
alcohol,  after  settling.   If  the  solution  remains  distinctly 
green,  an  aniline  color  is  present. 

319.  Insoluble    residue.     Digest    1    gram    with    dilute 
nitric  acid,  filter  and  wash  with  hot  water.     Residue  may 
consist  of  lead  sulphate,  barium  sulphate,  silica,  and  clay. 
Digest  residue  with  a  strong  solution  of  acid  ammonium 


182  ANALYSIS  OF  MIXED  PAINTS. 

acetate  in  order  to  dissolve  the  lead  sulphate;  filter,  wash 
with  hot  water.  To  the  filtrate  add  dilute  sulphuric  acid, 
evaporate  nearly  to  dryness.  Cool  and  take  up  with  water, 
filter  on  Gooch  crucible,  wash  with  50  per  cent  alcohol, 
ignite,  and  weigh  as  lead  sulphate.  The  residue  from  the 
ammonium  acetate  treatment  is  fused  with  sodium  car- 
bonate, and  the  barium,  alumina  and  silica  separated  as 
usual. 

320.  Lead  chromate.    The  nitric  acid  filtrate  is  treated 
with  1  c.c.  of  sulphuric  acid,  evaporated  nearly  to  dryness, 
cooled,  taken  up  with  water,  any  lead  sulphate  present 
filtered  off  and  calculated  to  lead  chromate. 

321.  Copper.     Dilute   the    filtrate    from   the   lead   sul- 
phate   to    about    200-250  c.c.     Pass    hydrogen    sulphide 
through  the  liquid  for  half  an  hour,  maintaining  the  tem- 
perature   at    70°  C.     Settle,    filter,    wash    with    hydrogen 
sulphide  water.    Transfer  filter  and  contents  to  a  250  c.c. 
beaker,  add  excess  of  strong  solution  of  sodium  sulphide, 
digest    for   30   minutes   at   a   gentle   heat.     Filter.     The 
residue  which  consists  of  copper  sulphide  is  dissolved  in 
dilute  nitric  acid  freed    from   sulphur  by  filtration,  and 
the  copper  determined  electrolyticalty  or  by  the  iodide 
method.     Calculate  to  cupric  oxide. 

322.  Arsenic.    The  arsenic  is  best  determined  as  de- 
scribed  above   under   the   estimation   of   total   arsenious 
oxide. 

323.  Chromium  and  zinc.     The  filtrate  from  the  copper 
and  arsenic  sulphides  is  boiled  to  thoroughly  expel  the 
hydrogen    sulphide,    ammonia    added    until    alkaline.    A 
greenish   precipitate  indicates  chromium,  a  white  precipi- 
tate, zinc  hydroxide.    In  the  latter   case    add    sufficient 
ammonia  to  redissolve  the  zinc.     Heat,  filter,  ignite  and 
weigh  as  chromium  oxide.    The  filtrate  from  the  chro- 
mium, or  the  solution  if  chromium  was  absent,  is  saturated 


ANALYSIS  OF  GREEN  PIGMENTS.  183 

with  hydrogen  sulphide  to  precipitate  the  zinc  as  sulphide, 
boil,  adding  5  grams  of  solid  ammonium  chloride  to  ren- 
der the  precipitate  less  slimy.  Dissolve  in  hydrochloric 
acid  and  titrate  with  standard  potassium  ferrocyanide 
as  described  under  analysis  of  white  pigments. 

324.  Calcium.     The  filtrate  from  the  zinc  is  boiled  to 
expel  hydrogen  sulphide  made  more  strongly  alkaline  with 
ammonia,  and  the  calcium  precipitated  with  ammonium 
oxalate  and  estimated  as  usual.    A  determination  of  sul- 
phates should  be  made  so   as   to   ascertain   whether  the 
calcium  was  present  as  carbonate  or  sulphate. 

325.  Magnesium.     If   a   considerable   quantity   of   cal- 
cium is  present  the  filtrate  from  the  calcium  is  tested  for 
magnesium,  which  if  found  is  estimated  as  usual. 

326.  Acetic  acid.    The  acetic  acid  may  be  obtained  by 
difference,  or  if  desired  estimated  by  C.  Mohr's  process  as 
described  in  Button's  Volumetric  Analysis. 

327.  ANALYSES  OF  A   PARIS  GREEN   BY   HURST. 

Water 0.90 

Copper  oxide 32 . 55 

Arsenious  acid 57.31 

Acetic  anhydride 6.63 

Sulphur  trioxide 1  67 

Undetermined  .  0.94 


100.00 


CHAPTER  XVI. 

EXERCISES  IN  COLOR    MAKING. 

328.  The  following  formulas  for  the  preparation  of  the 
more  common  colors  are  intended  only  for  the  analyst 
who  may  wish  to  acquire  a  little  insight  into  the  principles 
underlying  the  manufacture  of  colors  by  making  a  few 
experiments   for   himself.     The    formulas   used    by   color 
makers  are  kept  as  secret  as  possible,  and  probably  each 
manipulator  has  his  own  modifications  which  enable  him 
to  manufacture  colors  of  greater  strength  and  permanence 
to  light  than  any  novice  may  hope  to  do  in  a  set  of  beakers 
in  the  laboratory. 

329.  Para-nitroaniline  lake.    Seven  grams  of  para-nitro- 
aniline  is  added  to  15  grams  of  pure  concentrated  hydro- 
chloric acid  and  200  c.c.  of  water.    Heat  until  all  of  the 
para-nitroaniline  is  dissolved.     Cool  to  below  40°  F.  and 
then  slowly  and  with  constant  stirring  add  5  grams  of 
sodium  nitrite  dissolved  in  20  c.c.  of  water,  keeping   the 
solution   cool   with  ice.    Allow  to   stand   one-half  hour. 
Then  add  15  grams  of  sodium  acetate  dissolved  in  100  c.c. 
of  water  and  100  grams  of  inert  base,  like  blanc  fixe,  which 
has  been  thoroughly  freed  from  lumps. 

In  the  meanwhile  7  grams  of  beta-naphthol  are  dis- 
solved in  3  grams  of  sodium  hydroxide  and  175  c.c.  of 
boiling  water.  Cool  to  below  45°  F.  and  then  add  slowly 
and  with  constant  stirring  to  the  preparation  of  para- 
nitroaniline,  keeping  the  particles  of  blanc  fixe*  in  thorough 

184 


EXERCISES  IN  COLOR  MAKING.  185 

suspension.     The  lake  forms  at  once.     Wash  by  decanta- 
tion, filter,  and  dry  at  a  low  temperature. 

If  a  bluer  shade  is  desired  use  beta-naphthol  R. 

330.  Crimson   red   lake.     For   the   preparation   of   this 
lake   use   7  grams  of  alphanapthylamine  instead  of  the 
para-nitroaniline,    and    conduct    the    process    exactly    as 
described  under  the  manufacture  of  para-nitroaniline  lake, 
using  the  same  ingredients  and  the  same  amounts. 

331.  Emerald  green.     Dissolve  25  grams  of  cojDjper  sul^ 
phate  in  200  c.c.  of  water;  add  7  grams  sodium. crystals  or 
3.5  grams  of  the  dry  carbonate.     This  will  precipitate 
part  of  the  copper  as  copper  carbonate.     Then  add  just 
sufficient  acetic  acid  to  dissolve  the  copper  carbonate. 

In  a  separate  beaker  dissolve  15  grams  of  arsenious 
acid  and  22  grams  of  soda  crystals,  or  9.5  grams  of  dry 
carbonate,  in  150  c.c.  of  water.  Heat  both  solutions  to 
boiling  and  pour  the  arsenic  solution  slowly  and  evenly 
into  the  copper  solution  with  constant  stirring.  Wash  by 
decantation,  filter  and  dry. 

332.  Pale  lemon  chrome.   1.   Lead  solution.     Lead  ace- 
tate 50  grams  in  150  c.c.  of  water. 

2.  Bichromate  solution.     Dissolve  8  grams  of  sodium 
bichromate  in  100  c.c.  of  water. 

3.  Sulphuric  acid.     Dilute   8  grams  of  sulphuric   acid 
with  25  c.c.  of  water. 

Add  the  diluted  sulphuric  acid  to  the  sodium  bichromate 
solution  and  run  the  mixture  slowly  from  a  separating 
funnel  into  the  lead  acetate  solution,  with  constant  stir- 
ring. Settle,  wash  by  decantation  4  times,  filter,  dry  and 
grind. 

333.  Medium  chrome  yellow.     1.   Lead  solution.     Dis- 
solve 50  grams  lead  acetate  in  125  c.c.  of  water. 

2.  Bichromate  solution.  Dissolve  9  grams  of  sodium 
bichromate  in  75  c.c.  of  water. 


186  ANALYSIS  OF  MIXED   PAINTS. 

3.  Sulphuric  acid.  Dilute  6  grams  of  sulphuric  acid 
with  25  c.c.  of  water.  Precipitate  and  treat  as  described 
under  pale  lemon  chrome. 

Interesting  results  may  be  obtained  by  experimenting 
with  an  excess  of  each  ingredient,  precipitating  at  dif- 
ferent temperatures  and  with  different  concentrations. 

334.  American  vermilion — basic  lead  chromate.  1.  Lead 
solution.  Dissolve  50  grams  of  lead  nitrate  in  150  c.c. 
of  water. 

2.  Bichromate   solution.     Dissolve    17  grams   of   pow- 
dered sodium  bichromate  in  100  c.c.  of  water. 

3.  Slaked  lime.     Carefully  slake  6  grams  of  fresh  lime; 
reduce  to  a  thin  paste  in  a  mortar  until  free  from  lumpy 
particles. 

Place  the  bichromate  solution  in  a  separating  funnel 
and  allow  to  run  slowly  into  the  lead  nitrate  with  constant 
stirring.  Settle,  pour  off  the  supernatent  liquid.  Add 
the  lime  and  heat  to  boiling,  with  constant  stirring,  until 
the  required  shade  has  fully  developed.  Settle,  wash 
four  times  by  decantation,  filter,  dry  and  grind. 

335.   CHINESE   BLUE.     NUMBER   I. 

Grams. 

Potassium  ferrocyanide 25 

Ferrous  sulphate 25 

Potassium  bichromate 2 

Sulphuric  acid 12 

Potash  alum .    .       3 

Dissolve  the  ferrous  sulphate  and  alum  in  200  c.c.  of 
water.  Dissolve  the  ferrocyanide  in  200  c.c.  of  water 
and  run  the  iron  solution  into  it  with  constant  stirring. 
Run  in  the  dichromate  dissolved  in  25  c.c.  of  water,  and 
then  add  the  acid  with  constant  stirring.  Settle,  wash  by 
decantation  three  times,  filter  and  dry. 


EXERCISES  IN  COLOR  MAKING.  187 

336.   CHINESE   BLUE.     NUMBER  II 

Grams. 

Potassium  ferrocyanide 25 

Ferrous  sulphate 25 

Chloride  lime 5 

Sulphuric  acid 3 

Hydrochloric $ 

Dissolve  and  mix  the  ferrous  sulphate  and  ferrocyanide 
as  described  above.  Settle.  Draw  off  the  supernatent 
liquid,  and  add  the  chloride  of  lime,  dissolved  in  75  c.c.  of 
water,  through  a  fine  sieve.  Finally  add  the  sulphuric 
acid,  stir,  settle,  decant  three  times,  filter  and  dry. 

337.   CHINESE   BLUE.     NUMBER   III. 

Grams. 

Potassium  ferrocyanide 25 

Ferrous  sulphate 26 

Potassium  chlorate 4 

Sulphuric  acid       .    .      29 

Prepare  as  described  under  Chinese  Blue.    Number  I. 

338.  Brunswick  greens.  These  greens  are  prepared  by 
precipitating  the  yellow  first,  usually  on  an  inert  base 
like  barytes,  and  then  precipitating  the  blue  over  the 
yellow. 

Pale  green.  Precipitate  35  grams  of  chrome  yellow  on 
100  grams  of  barytes,  and  precipitate  1.5  grams  of  Prus- 
sian blue  on  the  yellow,  with  vigorous  stirring  in  each  case. 

Medium  green.  35  grams  chrome  yellow,  100  grams 
barytes  and  2.5  grams  of  Prussian  blue. 

Deep  green.  35  grams  of  chrome  yellow,  100  grams  of 
barytes  and  5  grams  of  Prussian  blue. 


CHAPTER  XVII. 

ANALYSIS   OF   JAPANS  AND  DRIERS. 

339.  At   the   present   time   the   terms    "  Japan "    and 
"  drier  "  are  interchangeable  and  refer  to  the  same  line 
of  products,  —  manganese  linoleate,  lead  lineolate,  resinate 
of  manganese,  resinate  of  lead,  or  mixtures  of  these  com- 
pounds.    Originally  Japan  contained  a  considerable  quan- 
tity of  dissolved  resin,  constituting  a  preparation  that  on 
drying  gave  a  film  of  considerable  hardness  and  lustre, 
but  this  distinction  has  largely  disappeared.    These  com- 
pounds should  not  be  confused  with  baking  Japans,  which 
represent   an   entirely   different    class   of    products   and 
which  will  not  be  discussed  at  this  time.     Japans  and 
driers  are  usually  made  by  heating  the  oxides  of  lead 
and  manganese  or  borate  of  manganese  with  linseed  oil 
or  the  various  resins,  and  dissolving  the  melted  mass  in 
turpentine,  benzine  or  mixtures  of  both. 

340.  Determination    of    the    drying    salts.     The    salts 
generally  used  are 

Litharge,  PbO 

Red  lead,  Pb303 

Oxide  of  manganese,   Mn02 
Borate  of  manganese,  MnB204 
occasionally  Zinc  sulphate,  ZnS04, 

and  Zinc  oxide,  ZnO. 

Weigh  25  grams  of  the  drier  into  a  250  c.c.  Erlenmeyer 
flask  and  dilute  with  25  c.c.  of  a  mixture  of  equal  parts  of 
benzine  and  turpentine.  Add  50  c.c.  of  dilute  hydro- 

188 


ANALYSIS  OF  JAPANS   AND   DRIERS.  189 

chloric  acid  (1.10  sp.  gr.)  Allow  to  stand  1  hour, 
shaking  thoroughly  at  intervals  of  10  minutes.  Immerse 
the  flask  in  a  beaker  of  hot  water,  at  a  considerable  dis- 
tance from  the  flame.  When  the  contents  of  the  flask 
are  hot,  shake  with  a  circular  motion,  avoiding  undue 
pressure  in  the  flask.  Allow  to  stand  until  cool,  so  as  to 
be  sure  that  the  drier  has  been  wholly  dissolved.  Pour 
into  a  separatory  funnel,  draw  off  the  aqueous  layer  into 
a  casserole,  wash  the  oil  portion  twice  with  warm  water, 
adding  the  washings  to  the  casserole  and  evaporate  to 
dryness  under  the  hood.  Dissolve  in  dilute  nitric  acid 
with  the  aid  of  heat,  filter  into  a  250  c.c.  graduated  flask 
and  after  washing  thoroughly  make  up  to  the  mark. 

341.  Lead.    To  an  aliquot  portion  add  5  c.c.  of  dilute 
sulphuric  acid  and  evaporate  on  the  hot  plate  until  white 
fumes  of  sulphur  trioxide  appear.     Cool,  add  cautiously 
50  c.c.  of  water,  heat  to  boiling,  cool  slightly,  and  add 
50  c.c.  of  alcohol.     Allow  to  stand  one-half  hour,  filter  on 
to  a  Gooch  crucible,  wash  with  50  per  cent  alcohol,  dry, 
heat  gently  and  weigh  as  lead  sulphate. 

342.  Manganese.    To  an  aliquot  portion  of  the  sample 
add  5  c.c.  of  sulphuric  acid  dilute  with  10  c.c.  of  water,  and 
evaporate  on  the  hot  plate  until  all  of  the  hydrochloric 
acid  is  expelled  as  shown  by  copious  evolution  of  sulphur 
trioxide  fumes.     Cool,  dissolve  in  about  25  c.c.  of   water 
and  heat  carefully  with  occasional  shaking  until  all  of  the 
anhydrous  sulphate  of  iron  has  dissolved.    Transfer  to  a 
250  c.c.  graduated  flask  and  add  an  excess  of  zinc  oxide 
emulsion,  obtained  by  mixing  C.  P.  zinc  oxide  with  water. 
Avoid  a  large  excess,  but  sufficient  to  precipitate  all  the 
iron,  so  that  on  standing  the  solution  begins  to  settle  clear 
and  some  zinc  oxide  can  be  seen  in  the  bottom  of  the 
flask.    Cool  and  make  up  to  the  mark.    Transfer  an  ali- 
quot portion  to  a  beaker  or  flask  and  add  an  excess  of  a 


190  ANALYSIS  OF  MIXED  PAINTS. 

saturated  solution  of  bromine  water,  and  about  3  grams  of 
sodium  acetate.  One  c.c.  of  a  saturated  solution  of  bromine 
water  will  precipitate  about  0.01  gram  of  manganese. 
Boil  about  2  minutes.  Filter  and  wash  with  hot  water. 
The  filtrate  must  be  perfectly  clear.  Place  the  filter  con- 
taining the  washed  precipitate  back  in  the  beaker  or  flask 
in  which  the  precipitation  was  made.  All  traces  of  bro- 
mine must  be  entirely  expelled. 

Add  an  excess  of  standard  oxalic  acid  solution  and 
about  50  c.c.  of  dilute  sulphuric  acid  (1:9)  and  heat  nearly 
to  boiling  with  gentle  agitation  until  the  precipitate  is 
entirely  dissolved.  Dilute  to  about  200  c.c.  with  hot 
water  and  titrate  with  standard  permanganate. 

343.  Zinc.     Zinc  sulphate  and  zinc  oxide  are  but  little 
used  at  present  in  driers.     If  present  zinc  may  be  esti- 
mated in  the  filtrate  from  the  lead  sulphate,  as  described 
under  the  analysis  of  mixed  paints  containing  umbers  and 
siennas. 

344.  Calculations.    The  color  of  the  drier  gives  a  clue 
as  to  the  combinations  used,  borate  of  manganese  being 
used  in  light  colored  driers,  oxide  of  manganese  in  dark 
driers,  and  the  oxides  of  lead  in  medium  colored  driers. 
By  far  the  most  common  combination  is  a  mixture  of 
borate  of  manganese  and  litharge. 

345.  Determination  of  the  volatile  oils.     Five  grams  of 
the  drier  is  quickly  weighed  into  a  flat-bottomed  dish,  a 
petri-plate  is  the  most  suitable,  dried  for  3  hours  at  150°  C., 
cooled   and   weighed.     Loss   in   weight    represents    very 
closely  the  amount  of  volatile  thinner  present,  and  in  the 
samples   analyzed    by   the   author   the   volatile   thinners 
constituted  63  to  68  per  cent  by  weight. 

346.  Separation  of  benzine  and  turpentine.    About  100 
grams  of  the  drier  is  distilled  to  the  point  of  incipient 
decomposition,  the  distillate  redistilled  and  the  benzine 


ANALYSIS    OF  JAPANS  AND  DRIERS.  191 

estimated   by  the  Sulphuric  Acid  Number,  as  described 
under  the  analysis  of  volatile  oils,  Chapter  IV. 

347.  Detection  of  rosin.     About  1.  c.c.  of  the  drier  is 
dissolved  in  15  c.c.  of  acetic  anhydride,  warming  until  the 
solution  is  complete.     Cool,  filter,  place  a  few  drops  of 
the  filtrate  on  a  crucible  cover  and  add  a  drop  of  sulphuric 
acid,  so  that  it  will  mix  slowly.     If  rosin  is  present  a  charac- 
teristic   fugitive    violet    color    results.     Lineolate    driers 
sometimes  give  a  color  resembling  that  of  rosin  driers,  and 
it  is  better  to  evaporate  a  portion  of  the  drier  to  a  syrup 
consistency,   treat   with   alcohol,   and   test   the   alcoholic 
extract. 

348.  Practical  tests.     The  chemical  analysis  of  a  Japan 
will  give  very  little  information  regarding  its  efficiency, 
since  the  latter  is  largely  dependent  upon  the  conditions  of 
manufacture.     The.  following  specifications,1    as   adopted 
and  used  by  the  Philadelphia  and  Reading  Railroad,  give 
very  excellent  methods  for  determining  the  efficiency  of  a 
Japan. 

"The  material  desired  consists  of  a  pure  turpentine 
hardener  and  oil  drier,  conforming  to  the  following: 

1st.  When  equal  parts  by  weight  of  the  Japan  and  of 
pure  turpentine  are  thoroughly  mixed  and  poured  over  a 
slab  of  glass,  which  is  then  placed  nearly  vertical  at  a  tem- 
perature of  100°  Fahrenheit,  with  a  free  access  of  air,  but 
not  exposed  to  draught,  the  coating  shall  be  hard  and  dry, 
neither  brittle  nor  sticky,  in  not  exceeding  12  minutes. 

2d.  When  thoroughly  mixed  with  pure  raw  linseed  oil 
at  the  ordinary  temperature  in  proportions  of  5  per  cent, 
by  weight  of  Japan  to  95  per  cent  by  weight  of  raw  linseed 
oil,  no  curdling  shall  result,  nor  any  marked  separation  or 
settling  on  standing. 

1  Practical  Testing  and  Valuation  of  Japan,  by  Robert  Job,  Chem- 
ical Engineer,  Vol.  IV.,  No.  5. 


192  ANALYSIS  OF  MIXED   PAINTS. 

3d.  When  the  above  mixture  is  flowed  over  a  slab  of 
glass,  which  is  then  placed  nearly  vertical,  at  a  temperature 
of  100°  Fahrenheit,  with  free  access  to  air,  but  not  exposed 
to  draught,  the  coating  shall  dry  throughout,  neither  brittle 
nor  sticky,  in  not  exceeding  2  hours. 

4th.  When  five  cubic  centimetres  of  the  Japan  are 
poured  into  95  cubic  centimetres  of  pure  turpentine  at 
the  ordinary  temperature,  and  thoroughly  shaken,  a  clear 
solution  shall  result,  without  residue,  on  standing  1  hour. 

5th.  After  evaporation  of  the  turpentine,  the  solid  resi- 
due must  be  hard  and  tough,  and  must  not  '  dust '  when 
scratched  with  a  knife. 

6th.  Benzine  or  mineral  oil  of  any  kind  will  not  be 
permitted. 

Shipments  which  are  not  closely  in  accordance  with 
these  specifications,  or  which  are  not  of  uniform  quality 
throughout,  will  be  returned  at  the  expense  of  the  shipper. " 

349.  The  temperature  of  100°  F.  is  obtained  by  the  use 
of  a  suitable  oven.  The  strips  of  glass  used  being  4  inches 
long  by  2  inches  wide.  They  are  so  placed  in  the  oven  that 
there  is  free  access  of  air,  but  no  draught.  The  bulb  of  the 
thermometer  is  placed  beside  the  glass  strips  and  the  dry- 
ness  of  the  film  tested  opposite  the  bulb  of  the  thermo- 
meter. 

The  addition  of  rosin  renders  the  dry  film  brittle  and 
hence  will  "  dust  "  when  scratched  with  a  knife. 

The  majority  of  driers  used  for  house  and  barn  paints 
are  weak  driers,  and  will  not  meet  the  above  requirements. 
However,  if  the  chemist  will  test  out  a  few  high-class 
driers  by  the  above  specifications,  he  will  have  but  little 
trouble  in  estimating  the  value  of  the  cheaper  and 
inferior  driers. 

The  United  States  Treasury  specifications  for  manganese 
borate  require  that  it  be  free  from  by-products,  and  that, 


ANALYSIS  OF  JAPANS   AND  DRIERS.  193 

other  properties  being  satisfactory,  preference  will  be 
given  to  the  article  containing  the  least  amount  of  alkali. 
Another  practical  test  much  in  vogue  among  practical 
painters  and  shop  foremen  is  to  make  a  semi-paste  with 
moisture-free  litharge  and  the  drier.  High-class  driers  will 
remain  three  to  four  days  before  showing  a  decided  ten- 
dency to  thicken  or  harden;  cheap  rosin  driers  will  begin 
to  harden  in  a  comparatively  short  time. 


CHAPTER  XVIII. 

ANALYSIS  OF   SHELLAC   AND   SPIRIT  VARNISHES. 

Analysis  of  Shellac. 

350.  The  most  common  adulterant  of  shellac  is  common 
rosin  or  colophony.     Sabin,  in  his  Technology  of  Paint  and 
Varnish,  says  that,  "  It  is  reported  and  probably  true,  that 
large  quantities  of  common  rosin  are  shipped  to  India  and 
used  as  an  adulterant  of  gum  shellac." 

351.  Detection  of  rosin.     About  1  gram  of  the  sample  is 
dissolved  in  about  15  c.c.  of  acetic  anhydride,  warming 
gently  until  the  solution  is  complete.     Cool  thoroughly 
under  the  tap.     The  rosin  will  remain  in  solution  while 
the  greater  part  of  the  shellac  will  separate  out.     Filter. 
Place  a  few  drops  of  the  filtrate  on  a  porcelain  crucible, 
cover,  and  add  by  means  of  a  stirring  rod  one  drop  of  sul- 
phuric acid  (34.7  c.c.  sulphuric  acid  and  35.7  c.c.  water) 
so  that  it  will  mix  slowly.     If  rosin  is  present  a  charac- 
teristic violet  fugitive  color  results.    A  pure  shellac  should 
give  no  coloration. 

352.  Estimation  of  rosin.     The  amount  of  rosin  present 
is  best  estimated  by  means  of  the  iodine  number.     For 
this  purpose  the  Hanus  method  is  to  be  preferred  to  the 
Hubl  or  Wijs  method.     The  Hubl  for  a  long  time  has  been 
the  official  method,  but  it  has  several  faults  which  affect  its 
accuracy.     It  rapidly  loses  strength  and  is  so  slow  in  its 
reaction  with  some  oils,  such  as  linseed  oil,  that  a  serious 
error  is  brought  about  by  the  change  in  strength  of  the 
solution  during  the  reaction.     Another  objection  to  the 

194 


ANALYSIS  OF  SHELLAC  AND  SPIRIT  VARNISHES.    195 

Hubl  method  is  that  practically  each  chemist  uses  a  mod- 
ification of  his  own  as  regards  the  time  necessary  for  the 
solution  to  remain  in  contact  with  the  substance  to  be 
tested. 

In  their  workings  the  Hanus  and  Wijs  methods  are  very 
similar,  but  the  Hanus  solution  is  much  easier  to  prepare 
and  the  results  obtained  more  nearly  correspond  to  those 
obtained  by  the  Hubl  method.  As  most  of  the  published 
data  relating  to  the  iodine  numbers  of  oils,  fats,  etc.,  has 
been  obtained  by  the  use  of  the  Hubl  method,  this  fact  is 
of  considerable  importance  in  making  comparisons. 

353.  The  Hanus  solution  is  prepared  and  used  as 
described  in  Chapter  IV. 

0.2  gram  to  0.3  gram  of  the  ground  sample  is  introduced 
into  a  250  c.c.  Erlenmeyer  flask;  20  c.c.  of  glacial  acetic 
acid  added,  and  the  mixture  warmed  until  the  solution 
is  complete,  except  for  the  wax.  10  c.c.  of  chloroform  is 
added,  the  solution  cooled  to  room  temperature,  and  25 
c.c.  of  Hanus  solution  added,  the  flask  stoppered,  allowed 
to  remain  in  the  dark  or  in  diffused  light  for  1  hour,  with 
occasional  shaking.  10  c.c.  of  potassium  iodide  solution 
is  then  added,  100  c.c.  of  water  and  titrated  with  tenth- 
normal  thiosulphate,  using  starch  as  an  indicator  in  the 
usual  manner.  Blank  determinations  should  be  made 
each  time. 

EXAMPLE: 

Wt.  of  sample  =  0.4  gram. 

A  blank  of  25  c.c.  of  Hanus  solution  required  55  c.c. 
of  thiosulphate. 

One  c.c.  of  thiosulphate  =  .0125  gram  of  Iodine.  Titration 
of  unabsorbed  iodine  =  49.5  c.c.  thiosulphate. 

55.0  —  49.5  =  5.5  c.c.  of  thiosulphate  equivalent  to 
iodine  absorbed. 


196 


ANALYSIS  OF  MIXED  PAINTS. 


(5.5  X  100  X  .0125)  -f-  0.4  =  17.2  per  cent  iodine 
absorbed. 

354.  Iodine  Numbers  of  shellacs  obtained  from  the 
leading  wholesalers  and  jobbers  of  the  United  States,  sup- 
posed to  be  strictly  pure:1 


No. 

Variety. 

Iodine 
No. 

Color 
Reaction.2 

1 
2 
3 

Orange  shellac  
Unbleached  shellac  
Orange  shellac  .  . 

31.06 
15.85 
12  68 

Rosin  present. 
Rosin  absent. 
Rosin  absent 

4 

Ralle  standard  shellac  .... 

16  80 

Rosin  absent 

5 

Star  brand  shellac  

14  90 

Rosin  absent 

6 
13 

H.  N.  superior  shellac  
Orange  shellac  

12.99 
22.27 

Rosin  absent. 
Rosin  present 

14 
15 
16 
17 

Orange  shellac  
Orange  shellac  » 
Orange  shellac  
Orange  shellac  

20.36 
16.54 
20.36 
13.36 

Rosin  absent. 
Rosin  absent. 
Rosin  absent. 
Rosin  absent. 

7 
8 
9 
10 
12 

Bone  Dry  bleached  shellac  
Refined  bone  dry  bleached  shellac 
Bleached  shellac     
Bleached  shellac     
Bleached  shellac     

8.87 
12.34 
6.34 
8.87 
13.36 

Rosin  absent. 
Rosin  absent. 
Rosin  absent. 
Rosin  absent. 
Rosin  absent 

Analysis  of  Shellac  Varnish. 

355.  Composition.  A  varnish  having  the  proper  con- 
sistency is  prepared  by  dissolving  45  parts  of  shellac  in  55 
parts  of  grain  alcohol  of  94  per  cent  strength  or  about  5 
pounds  of  shellac  per  gallon  of  alcohol.  In  place  of  the 
expensive  grain  alcohol,  some  manufacturers  substitute 
wood  alcohol  or  Columbian  spirits,  which  is  rectified  wood 
alcohol.  The  poisonous  properties  of  wood  alcohol  are 
well  known,  and  on  account  of  its  injurious  effects  great 
care  should  be  exercised  in  the  use  of  varnishes  containing 
it.  Shellac  varnish  is  often  adulterated  with  rosin,  thus 
producing  a  product  of  an  inferior  quality.  The  sophis- 

1  Analyses  by  author. 

2  Libermann-Storch  Reaction. 


ANALYSIS  ON  SHELLAC  AND  SPIRIT   VARNISHES.     197 

tication  of  varnish  with  this  substance  is  well  described  by 
Langmuir:1  "  Starting  out  with  an  adulterated  shellac,  the 
varnish  maker,  secure  in  his  belief  that  rosin  cannot  be 
detected  in  the  solution,  proceeds  to  add  still  more  rosin. 
What  has  been  said  in  regard  to  adulteration  of  shellac 
fades  into  insignificance  in  comparison  with  that  practice 
in  the  manufacture  of  shellac  varnishes.  Shellac  varnishes 
are  sold  containing  no  shellac.  '  Pure  '  shellac  varnishes, 
grain  alcohol,  may  be  purchased  at  less  cost  than  the 
alcohol." 

356.  Determination   of   the   body   of   shellac   varnishes. 
Three  to  5  grams  of  the  well  stirred  sample  is  weighed  into 
a  weighed  flat-bottomed  petri-dish  and  evaporated  to  a 
constant  weight  in  the  steam  oven.     The  result  is  calcu- 
lated in  pounds  per  gallon.     If  a  platinum  evaporating 
dish  be  used  and  the  evaporation  conducted  over  a  water 
bath,  the  amount  taken  should  not  be  over  1  gram.     Tak- 
ing the  weight  of  a  gallon  of  wood  alcohol  at  60°F.   as 
6.75  pounds,  the  pounds  per  gallon  may  be  ascertained  by 
means  of  the  following  table : 2 

Per  cent.  Pounds 
Residue.                                                                                   per  Gallon. 

30.77  3.0 

34.15  3.5 

37.20  4.0 

40.00  4.5 

42.55  5.0 

44.90  5.5 

47.06 6.0 

49.05  6.5 

50.91  7.0 

52.63  7.5 

54.23  8.0 

357.  Determination  of  the  strength  of  the  alcohol  used. 

The  strength  of  the  alcohol  may  be  calculated,  knowing  the 

1  Determination  of  Rosin  in  Shellac,  J.  Soc.  Chem.  Ind.,  January  1, 
1905. 

2  Determination  of  Rosin  in  Shellac,  J.  Soc.  Chem.  Ind.,  January  L 
1905. 


198  ANALYSIS  OF  MIXED  PAINTS. 

per  cent  of  residue  as  determined  above  and  the  specific 
gravity  of  the  varnish.  The  calculation  is  best  illustrated 
by  the  following  example: 

5  grams  of  varnish  yielded  a  residue  of  2.300  grams. 

The  specific  gravity  of  the  varnish  was  0.9445  at  15.5°  C. 

100  grams  of  the  varnish  gave  2.300  X  20  =  46.00  grams 
of  residue  or  46.00  per  cent. 

The  alcohol  by  difference  100.00  -  46.00  =  54.00  grams 
or  54.00  per  cent. 

Average  specific  gravity  of  shellac  itself  =  1.145. 

The  volume  taken  up  by  the  shellac  in  the  varnish  would 
be  46.00-5-1.145  =  40.17  c.c.  in  100  grams  of  varnish. 

The  specific  gravity  of  the  varnish  was  0.9445. 

100  c.c.  would  weigh  94.45  grams  and  hence  100  grams 
would  occupy  105.9  c.c. 

105.9  c.c.  —  40.17  c.c.  =  65.73  c.c.,  the  volume  occu- 
pied by  54.00  grams  of  alcohol  solvent. 

54.00  •+•  65.73  -  0.8215,  the  specific  gravity  of  the  alcohol. 
From  the  alcohol  tables  this  will  be  found  to  correspond 
to  90.5  per  cent  of  grain  alcohol.  If  desired  a  portion 
of  the  varnish  may  be  distilled  until  the  decomposition 
point  is  reached  and  the  strength  of  the  alcohol  determined 
from  the  specific  gravity  of  the  distillate. 

358.  Examination  of  the  solvent.     One  hundred  grams 
of  the  varnish  is  carefully  distilled  to  the  point  of  incipient 
decomposition.      If  necessary  the   distillate   may  be   re- 
distilled. 

359.  Detection  of  benzine.     Dilute  a  portion  of  the  dis- 
tillate with  three  or  four  volumes  of  water.    If  benzine  is 
present  it  will  separate  out. 

360.  Columbian  spirit  and  wood  alcohol.    The  test  for 
acetone,  which  is  always  to  be  found  in  wood  alcohol, 
will    distinguish    between  Columbian    spirit    and    wood 
alcohol. 


ANALYSIS  OF  SHELLAC  AND  SPIRIT  VARNISHES.      199 

361.  Detection    and    estimation    of    wood    alcohol    in 
mixtures  with  grain  alcohol.     Qualitatively,  the  methyl 
alcohol  may  be  detected  by  the  following  method : 

Dilute  a  portion  of  the  distillate  until  the  liquid  con- 
tains approximately  12  per  cent  of  alcohol  by  weight. 

Oxidize  10  c.c.  of  the  liquid  in  a  test  tube  as  follows: 
Wind  copper  wire  1  m.m.  thick  upon  a  rod  or  pencil  7  to 
8  m.m.  thick  in  such  a  manner  as  to  enclose  the  fixed  end 
of  the  wire  and  to  form  a  close  coil  3  to  3.5  cm.  long.  Twist 
the  two  ends  of  the  wire  into  a  stem  20  cm.  long  and  bend 
the  stem  at  right  angles  about  6  cm.  from  the  free  end, 
or  so  that  the  coil  may  be  plunged  to  the  bottom  of  a 
test  tube,  preferably  about  16  m.m.  wide  and  16  m.m.  long. 
Heat  the  coil  in  the  upper  or  oxidizing  flame  of  a  Bunsen 
burner  to  a  red  heat  throughout.  Plunge  the  heated  coil 
to  the  bottom  of  the  test  tube  containing  the  diluted 
alcohol.  Withdraw  the  coil  after  a  second 's  time  and 
dip  it,  in  water.  Repeat  the  operation  from  three  to  five 
times,  or  until  the  film  of  copper  oxide  ceases  to  be  reduced. 
Cool  the  liquid  in  the  test  tube  meanwhile  by  immersion 
in  water. 

362.  Add   1   c.c.  of  strong  ammonia  to  the  oxidized 
liquid  in  a  casserole  and  expel  the  acetaldehyde  by  boiling 
gently  over  a  direct  flame  until  the  vapor  ceases  to  smell 
of  ammonia.    Add  2  to  3  drops  of  strong  hydrochloric 
acid  to  set  free  the  formaldehyde  which  has  been  retained 
as  hexamethyltetramin,  and  brmg  the  liquid  momentarily 
to  a  boil;  cool  promptly  by  immersion  of  the  casserole  in 
water  and  test  for  formaldehyde  by  the  modified  resorcin 
test,  as  follows: 

Adc?  to  the  liquid  remaining  1  drop  of  a  solution  con- 
taining 1  part  of  resorcin  in  200  parts  of  water,  and  pour 
the  mixture  cautiously  into  a  test  tube  containing  3  c.c. 
of  concentrated  sulphuric  acid,  holding  the  tube  in  an 


200  ANALYSIS    OF    MIXED    PAINTS. 

inclined  position  in  such  a  manner  that  the  two  liquids 
shall  not  mix.  Allow  it  to  stand  3  minutes,  then  sway 
the  tube  slowly  from  side  to  side  in  such  a  manner  as  to 
produce  a  gentle  rotary  motion  of  the  two  layers.  Persist 
in  this  operation,  if  necessary,  for  a  minute  or  more,  using 
a  piece  of  white  paper  for  a  background,  and  producing 
only  a  very  gradual  and  partial  mixing  of  the  acid  and 
water.  Nearly  half  of  the  acid  should  remain  as  a  dis- 
tinct unmixed  layer  at  the  end.  When  methyl  alcohol  is 
present,  the  shaking  causes  the  separation  of  more  or  less 
voluminous  flocks  of  a  very  characteristic  rose-red  color. 
The  appearance  of  colored  zones  or  flocks  of  other  hues, 
even  when  tinged  with  red,  or  of  a  rose-red  solution 
without  flocks,  should  never  be  considered  proof  of 
the  presence  of  methyl  alcohol.  However,  if  the  flocks 
are  reddish  brown,  or  if  the  upper  layer  has  a  pronounced 
red,  it  is  often  well  to  repeat  the  test. 

By  this  method  for  the  removal  of  acetaldehyde  10 
per  cent  of  methyl  alcohol  may  be  readily  detected,  and 
an  experienced  operator  may  detect  with  certainty  a  less 
amount. 

363.  Quantitatively  the  methyl  alcohol  may  be  esti- 
mated by  the  method  of  Thorp  and  Homes. 

This  method  depends  upon  the  fact  that  in  the  presence 
of  potassium  dichromate  and  sulphuric  acid  in  a  closed 
vessel  at  100°,  ethyl  alcohol  is  converted  into  its  theoretical 
equivalent  of  acetic  acid,  while  with  methyl  alcohol,  the 
product  resulting  from  the  oxidation  is  always  carbon 
dioxide  and  water.  It  has,  however,  been  found  that  for 
each  gram  of  ethyl  alcohol  present  in  the  solution  0.01 
'gram  of  carbon  dioxide  may  be  formed,  and  this  correction 
should  be  made  in  all  determinations. 

The  specific  gravity  is  determined  by  means  of  a  pycno- 
meter.  The  total  per  cent  of  the  alcohol  is  practically  the 


ANALYSIS  OF  SHELLAC  AND  SPIRIT  VARNISHES.     201 

same  as  the  per  cent  of  ethyl  alcohol  of  the  same  specific 
gravity. 

364.  The  methyl  alcohol  is  determined  by  converting 
it  into  carbon  dioxide  by  means  of  sulphuric  acid  and 
potassium  dichromate  in  the  Knorrs'  apparatus  described 
under  the  estimation  of  carbon  dioxide  in  white  lead. 

Weigh  into  the  flask  20  grams  of  potassium  dichro- 
mate, connect  the  apparatus  after  having  weighed  the 
soda-lime  tubes.  Introduce  through  the  stop-cock  funnel 
an  exact  volume  of  the  alcohols  not  to  exceed  4  grams 
of  the  mixed  alcohols,  and  an  amount  of  water  equal  to 
50  c.c.  less  the  number  of  c.c.  of  alcoholic  solution,  80 
c.c.  of  sulphuric  acid  (made  by  diluting  one  volume  of 
concentrated  acid  with  four  volumes  of  water)  are  added, 
well  shaken  and  allowed  to  stand  18  hours.  Dissolve 
10  grams  of  potassium  dichromate  in  50  c.c.  of  water, 
add  through  the  funnel,  then  add  50  c.c.  of  concen- 
trated sulphuric  acid  and  heat  the  contents  of  the  flask 
to  boiling  for  about  ten  minutes,  the  carbon  dioxide  being 
carried  off  by  a  current  of  air  through  the  apparatus. 
The  heat  is  now  removed  and  the  current  of  air  continued 
for  a  few  minutes  longer.  Disconnect  and  weigh  the 
soda-lime  tubes. 

Calculate  the  methyl  alcohol  from  the  proportion 

1.373  : 1  :  :  wt.  C02  obtained  :  x 
x  =  wt.  methyl  alcohol, 

the  theoretical  oxidation  of  1  gram  methyl  alcohol  pro- 
ducing 1.373  grams  of  carbon  dioxide. 

EXAMPLE. 

Specific  gravity  of  sample,  0.7992 

Weight  of  sample  used,  1.0118  grams 

Weight  of  carbon  dioxide,  1.3810  grams 


202  ANALYSIS   OF  MIXED   PAINTS. 

1.373:1  :  :  1.3810  :  x 

x  =  1.006  grams  methyl  alcohol. 

1.0118  : 1.006  :  :  100  :  y 

y  =  99.4  per  cent  methyl  alcohol. 

365.  If  ethyl  alcohol  is  present,  the  correction  previously 
referred  to,  of  0.01  gram  carbon  dioxide  for  each  gram  of 
ethyl  alcohol,  should  always  be  applied.     The  weight  of 
the  methyl  alcohol  subtracted   from  the   weight  of  the 
mixed  alcohols    (calculated   from  the  sp.  gr.)   gives  the 
weight  of  the  ethyl  alcohol,  approximately.     The  weight 
obtained  by  0.01  gives  correction  to  be  deducted  from  the 
total  carbon  dioxide,  for  the  recalculation  of  the  weight  of 
methyl  alcohol.      It  is  obvious  that  a  very  slight  error  is 
thus  introduced,  but  the  writer  believes  that  it  is  so  small 
that  it  may  be  safely  neglected. 

366.  Detection   and   estimation   of   rosin.     The   residue 
remaining  after  the  drying  of  the  varnish  in  the  determi- 
nation of  the  "  body  "  may  be  used  for  the  detection  of 
rosin  as  described  under  the  examination  of  shellac. 

If  much  rosin  is  present,  it  is  not  safe  to  take  the  residue 
after  evaporation  for  the  quantitative  estimation  as  has 
been  shown  by  Langmuir.  "  A  little  rosin  (iodine  value 
224.3)  was  dissolved  in  alcohol,  evaporated  on  the  water 
bath  and  heated  5  hours.  It  then  showed  a  value  of  148.2. 
Similarly,  a  dark  rosin  175.7  fell  to  131." 

A  quantity  of  the  varnish  sufficient  to  yield  0.2  to  0.4 
gram  of  residue  is  weighed  from  a  small  vial,  provided 
with  a  perforated  stopper  carrying  a  shortened  1  c.c. 
pipette,  into  a  200  c.c.  Erlenmeyer  flask;  the  weight  of  the 
sample  used  being  thus  obtained  by  difference.  The  sam- 
ple in  the  flask  is  carefully  evaporated  at  a  low  temperature 
until  pasty  and  then  dissolved  in  the  requisite  amount  of 
acetic  acid  and  chloroform  and  the  iodine  number  then 


ANALYSIS  OF  SHELLAC  AND  SPIRIT  VARNISHES.     203 

determined  in  the  usual  manner.  The  error  due  to  the 
action  of  the  small  amount  of  alcohol  remaining  in  the 
pasty  mass  on  the  thiosulphate  is  negligible. 

In  calculating  the  per  cent  of  rosin  the  iodine  values  of 
150 l  for  rosin,  16  *  for  unbleached  and  II1  for  bleached 
shellac  may  be  used.  If  other  resins  are  present,  as  san- 
darac,  etc.,  these  can  only  be  calculated  in  the  terms  of 
rosin. 

367.  Estimation  of  rosin,  Mannhardt's  method.2    Five 
grams  of  gum  shellac  or  10  grams  of  shellac  varnish  are 
weighed  into  a  casserole  or  flask,  and  the  solvent  expelled 
on  the  water-bath.   The  residue  is  saponified  with  alcoholic 
potash,  the  alcohol  expelled,  and  the  residue  taken  up  in 
100  c.c.  of  hot  water.     At  this  point  any  wax  present  may 
be   extracted    with    benzine  (sp.   gr.    .730),  the    benzine 
evaporated  off,  and  the  residue  weighed. 

The  solution  of  the  soaps  is  treated  with  50  c.c.  benzine 
(sp.  gr.  .730),  shaken  vigorously,  and,  before  the  emulsion 
has  time  to  separate  out,  add  dilute  sulphuric  acid  in 
slight  excess.  The  shellac  acids  immediately  coagulate, 
and  all  rosin  acids  go  into  the  benzine,  which  is  readily 
separated,  filtered  and  evaporated  in  a  weighed  beaker. 
The  shellac  acids  are  absolutely  insoluble  in  benzine. 
Damar  and  possibly  sandarac  will  behave  like  rosin. 

368.  Practical  test  for  brewers'  varnish.     Varnishes  for 
brewers'  purposes  should  be  made  from  pure  shellac  and 
grain  alcohol  94  per  cent  strength.     They  may  be  tested 
out  by  varnishing  a  strip  of  wood  6  inches  long  by  3  inches 
wide,  and  a  quarter  of  an  inch  in  thickness,  and  after  drying 
immerse  half  of  the  strip  in  4  per  cent  alcohol  for  48  hours. 
A  varnish  made  from  impure  shellac  or  alcohol  of  less  than 
the  proper  strength  will  soon  turn  white. 

1  Average  values  obtained  by  author. 

2  Hans  Mannhardt,  Chemist,  Heath  &  Milligan  Mfg.  Co. 


204  ANALYSIS  OF  MIXED  PAINTS. 

369.   ANALYSES  OF  SHELLAC   VARNISHES.1 


No. 

Variety. 

Iodine 
Number. 

Percentage 
of  Gum. 

Calculated 
Percentage 
Rosin. 

18 

Orange  shellac          .    .    . 

40.5 

49.8 

18.3 

19 

Orange  shellac      .... 

13.4 

42.2 

23 

Orange  shellac      .... 

26.2 

37.1 

7.62 

25 

Orange  shellac      .... 

16.2 

35.9 

.  .  . 

26 

Orange  shellac      .... 

15.2 

21.0 

. 

27 

Orange  shellac      .... 

37.4 

13.3 

16.6 

29 

Orange  shellac      .... 

23.3 

40.5 

5.42 

31 

Orange  shellac      .... 

15.0 

39.8 

20 

White  shellac        .... 

40.8 

44.1 

2i!4 

30 

White  shellac        .... 

37.8 

22.4 

19.3 

21 

White  shellac        .... 

13.3 

41.0 

22 

White  shellac        .... 

16.2 

37.6 

28 

White  shellac       .... 

17.5 

42.0 

370.  Damar    varnish.       The     following     specifications 
adopted  by  the  Navy  Department,  May,  1904,  will  serve 
for  the  practical  testing  and  valuation  of  damar  varnish. 

Damar  varnish  must  be  made  from  the  very  best  quality 
of  damar  gum  in  a  solution  containing  at  least  50  per  cent 
of  gum  and  45  per  cent  of  turpentine,  the  gum  to  be  digest- 
ed cold  and  well  settled.  The  varnish  must  be  as  clear  as 
and  not  darker  than  the  standard  sample,  and  must  be 
free  from  benzine,  rosin,  lime,  or  other  mineral  matter. 
Its  specific  gravity  at  60°  F.  must  be  about  0.950,  and 
its  flash  point  between  105°  and  115°  F.  It  must  set  to 
touch  in  not  more  than  20  minutes,  and  when  mixed  with 
pure  zinc  oxide  must  show  a  smooth  glossy  surface  equal  to 
that  shown  by  the  standard  sample. 

371.  Tests.     Besides  chemical  tests  to  determine  the 
above  qualities,  and  practical  tests  to  determine  its  quali- 
ties of  finish,  a  board  properly  coated  with  a  mixture  of 

1  Analyses  by  author. 

2  Liebermann-Storch  reaction  produces  a  somewhat  different  color 
than  that  usually  given  by  rosin,  hence  these  samples  may  be  adulter- 
ated with  other  gums. 


ANALYSIS  OF  SHELLAC  AND  SPIRIT  VARNISHES.     205 

zinc  and  the  liquid  will  be  exposed  to  the  weather  for  a 
period  of  1  month,  and  at  the  end  of  this  time  must  have 
stood  exposure  equally  as  well  as  the  standard  sample.  A 
similarly  prepared  sample  will  also  be  baked  at  250°  F., 
and  must  not  at  this  temperature  show  any  greater  signs 
of  cracking,  blistering,  or  any  other  defects  than  standard 
samples  under  the  same  conditions.  Another  sample, 
similarly  prepared,  will  be  exposed  in  a  dark  room  at  ordi- 
nary temperature  for  a, period  of  1  month  and  at  the  end 
of  this  time  must  not  have  turned  darker  to  any  appre- 
ciable degree  than  the  standard  sample. 


CHAPTER  XIX. 

ANALYSIS  OF  OIL  VARNISHES. 

372.  Analysis  of  oil  varnishes.    As  stated   by  Hurst, 
"  The  analysis  of  oil  varnishes  is  one  of  great  difficulty,  as 
it  is  quite  impossible  to  separate  all  the  ingredients  from 
one  another. J;    However  in  spite  of  the  unsatisfactory 
state  of  our  present  knowledge  of  varnish  analysis,  a  dis- 
tillation and  separation  will  give  an  approximate  idea  of 
the  quantity  and  kind  of  volatile  solvents  used.    Treating 
the  residue  by  Twitchell's  method ,  will  give  approximately 
the  amount  of  oil  and  the  amount  of  gum  present  in  the 
varnish  and  an  examination  of  the  physical  and  chemical 
properties  of  the  separated  gum  may  give  an  approximate 
idea  of  its  hardness,  and  throw  some  little  light  on  its 
probable  source.     The  presence  of  lime,   color  produced 
by  the  Liebermann-Storch  reaction,  acid  figure  and  iodine 
absorption  will  indicate  the  presence  of  rosin  and  to  some 
extent  the  amount  present.     With  these  tests,  in  conjunc- 
tion with  the  solubility  of  the  separated  gum,  the  original 
character  of  the  varnish,  e.g.,  the  pouring  of  a  portion  of 
the  sample  on  a  sheet  of  glass,  noting  how  it  flows,  dries, 
the  kind  of  film  produced,  its  resistance  to  abrasion,  to 
moisture,  its  elasticity,  etc.,  and  a  comparison  made  with 
varnishes  of  known  composition  and  similar  properties,  a 
very  shrewd  guess  can  be  made  as  to  how  the  varnish  under 
consideration  must  be  duplicated,  or  in  other  words,  the 
approximate  amounts  of  the  different  gums  required  to 
produce  a  similar  product. 

373.  On  the  other  hand,  a  proximate  analysis  of  a  var- 

206 


ANALYSIS  OF  OIL  VARNISHES.  207 

nish  furnishes  us  with  but  a  small  amount  of  helpful  infor- 
mation, as  the  gloss,  working  qualities,  and  durability 
depend  largely  on  the  quality  of  gum  used,  the  quality 
and  treatment  of  the  oil,  the  quality  of  the  driers  used, 
and  especially  as  to  how  the  varnish  was  prepared,  as 
regards  heat,  method  of  cooking,  ageing,  filtering,  etc. 
On  these  essential  points  a  chemical  analysis  tells  us  but 
little.  That  greater  light  will  eventually  be  thrown  on 
the  problems  involved,  the  author  has  not  the  slightest 
doubt,  but  meanwhile  interpretations  based  solely  on 
chemical  analyses  are  liable  to  be  more  or  less  misleading; 
but  taken  in  connection  with  physical  tests,  carefully 
made,  the  value  of  varnishes  can  be  determined  with 
considerable  accuracy. 

374.  Specific  gravity.    The  determination  of  the  specific 
gravity  is  of  considerable  importance  and  should  be  made 
with  a  pycnometer  at  15.5°  C. 

375.  Viscosity.    The  determination  of  the  viscosity  of 
a  varnish  will  throw  considerable  light  on  its  working 
qualities.     Any   of  the   standard   types   of  viscosimeters 
may  be  used  for  varnish  work,  but  the  Doolittle  Torsion 
Viscosimeter  offers  several  advantages  over  the  others. 

376.  Separation,    identification,    and    estimation   of   the 
volatile  oils.    Seventy-five  grains  of  a  uniform  sample  of 
the  varnish  is  weighed  into  a  500  c.c.  distilling  flask,  pro- 
vided with  a  tube  leading  very  nearly  to  the  bottom,  the 
other  end  of  which  is  connected  with  a  steam  supply. 
The  flask  is  also  provided  with  a  thermometer,  the  bulb  of 
which  dips  below  the  surface  of  the  varnish,  and  the  flask 
then  connected  with  a  rather  long  condenser.     By  means 
of  an  oil  bath  the  varnish  is  heated  to  130°  C.,  and  a  cur- 
rent of  steam  passed  through,  until  about  500  c.c.  of  water 
has  passed  over,  or  until  the  steam  ceases  to  carry  over 
any  more  volatile  oil.     It  is  advisable  to  collect  the  dis- 


208  ANALYSIS  OF  MIXED  PAINTS. 

tillate  directly  in  a  separating  funnel.  When  the  volatile 
oil  has  completely  settled  out,  the  water  is  drawn  off  and 
the  oil  transferred  to  a  weighed  flask,  weighed,  and  the 
percentage  calculated.  The  aqueous  distillate  will  con- 
tain a  small  quantity  of  the  volatile  oil  equal  to  about 
0.4  gram  per  hundred  c.c.  This  correction  should  be 
made  in  calculating  the  percentage. 

The  constituents  of  the  volatile  oil  and  the  amount  of 
petroleum  products  present  may  be  determined  exactly 
as  described  in  the  chapter  on  the  Analysis  of  the  Vehicle 
of  Mixed  Paints. 

377.  Separation  of  the  resin  gums  from  the  oil, 
Twitchell's  method.  The  flask  containing  the  residue  of 
oil  and  gum  is  connected  with  a  return  condenser,  150  c.c. 
of  normal  alcoholic  potash  added,  the  flask  heated  care- 
fully on  a  water  bath  to  avoid  bumping  and  finally  heated 
over  a  free  flame  for  about  an  hour.  The  solution  is  then 
cooled  and  separated  from  the  residue,  which  is  again 
treated  with  alcoholic  potash,  and  the  process  continued 
until  as  complete  a  saponification  as  possible  has  been 
made;  usually  a  small  residue  of  about  1  per  cent  remains. 
The  different  alcoholic  solutions  are  united,  neutralized 
with  hydrochloric  acid,  the  excess  of  alcohol  evaporated 
off,  and  the  fatty  acids  and  gums  removed  with  succes- 
sive portions  of  ether.  The  ethereal  solution  is  distilled 
to  remove  the  ether,  a  small  quantity  of  absolute  alcohol 
added,  and  the  flask  again  heated  gently,  the  alcohol 
carrying  off  the  last  traces  of  water.  About  10  volumes 
of  absolute  alcohol  are  added  to  the  dry  gums  and  acids, 
the  solution  being  kept  cold  by  ice  and  dry  hydrochloric 
acid  gas  is  passed  in  until  the  solution  is  saturated.  This 
will  usually  take  from  30  to  45  minutes.  The  flask  and 
contents  are  allowed  to  stand  for  about  an  hour,  then 
diluted  with  about  5  volumes  of  hot  water,  and  boiled 


ANALYSIS  OF  OIL  VARNISHES.  209 

until     clear;    the    heating    being    conducted     gently     to 
avoid  frothing. 

378.  The  contents  of  the  flask  are  mixed  with  a  little 
petroleum  ether,  boiling  below  80°  C.  and  transferred  to 
a  separating  funnel,  the  flask  being  washed  out  with  the 
same  solvent.    The  petroleum  ether  layer  should  measure 
about  50  c.c.    After  shaking,  the  acid  solution  is  run  off 
and  the  petroleum  ether  layer  washed  once  with  water, 
and  then  treated  in  the  funnel  with  a  solution  of  2.5  grams 
of  potassium  hydroxide  and  20  c.c.  of  alcohol  in  200  c.c. 
of  water.     The  cthylic  esters  dissolved  in  the  petroleum 
ether  will  then  be  found  to  float  on  top,  the  rosin  acids 
having  been  extracted  by  the  dilute  alkaline  solution  to 
form  rosin  soap.    The  soap  solution  is  then  run  off,  decom- 
posed  with  hydrochloric   acid,   and   the   separated   rosin 
acids  collected  as  such,  or  preferably  dissolved  in  ether, 
and  the  whole  evaporated  in  a  small  weighed  beaker  on 
the  water  bath.     A  small  quantity  of  absolute  alcohol  is 
added,  and  the  evaporation  repeated.     Finally,  cool  in  the 
desiccator  and  weigh.     This  will  give  approximately  the 
amount  of  gums   present  in  the   varnish.     Any  residue 
insoluble   in  the   10  volumes  of  absolute  alcohol  above 
mentioned  is  weighed  up  and  its  weight  added  to  the 
weight  of  resin  gum. 

379.  Separation    of    the    gums    from    the    oil,     Scott's 
Method.1     In  separating  the  gum,  by  this  method,  it  is 
necessary  to  know  whether  the  sample  is  a  Long  Oil  or 
Short  Oil  Varnish,  i.e.,  whether  it  contains  a  large  or 
small  amount  of  linseed  oil.     Hard  oil  finishes,  interior 
varnishes,  and    rubbing  varnishes    are    usually  shot    oil 
varnishes,  while  carriage  and  similar  varnishes  are  long  oil 
varnishes. 

In  order  to  determine  to  which  class  a  varnish  belongs, 
1  Drugs,  oils,  and  paints,  XV.,  No.  4,  p.  132,  and  No.  6,  page  219. 


210  ANALYSIS  OF  MIXED  PAINTS. 

about  10  c.c.  of  the  sample  is  poured  into  a  beaker  and 
50  c.c.  of  benzine,  previously  cooled  to  about  5°  C.,  added. 
If  the  sample  be  short  oil  varnish  the  gums  will  be  partially 
precipitated,  while  a  long  oil  varnish  will  show  but  little 
change.  The  color  of  the  precipitated  gum  may  be  con- 
sidered as  another  indication,  a  light  colored  precipitate 
denoting  a  short  oil,  and  a  dark  colored  preciptate,  a  long 
oil  varnish. 

380.  Short  oil  varnishes.    A  beaker  of  about  150  c.c. 
capacity,  provided  with  a  stirring  rod,  is  carefully  weighed, 
and  about  10  grams  of  varnish  weighed  into  it.     Cool  to 
below  10°  C.     Fifty  c.c.  of  petroleum  ether  that  has  pre- 
viously been  cooled  to  below  3°  C.  is  poured  into  the 
beaker  and  the  contents  stirred.    The  beaker  is  placed  in 
a  freezing  mixture  for  about  an  hour,  or  until  the  precipi- 
tated gums  have  settled. 

381.  Place  a  filter  paper  that  has  been  dried  in  the 
oven,  in  the  suction  funnel.     Moisten  and  suck  the  filter 
free  from  surplus  moisture,  pour  in  the  gasoline,  retaining 
as  much  of  the  resins  as  possible  in  the  beaker.     Add 
another  50  c.c.  of  ice  cold  petroleum  ether,  and  allow  to 
stand  as  before  in  the  freezing  mixture.     Meanwhile  pour 
25  c.c.  of  ice  cold  water  on  the  filter  paper,  allowing  it  to 
run  into  the  petroleum  ether  filtrate,  which  is  then  vig- 
orously shaken  up  so  as  to  thoroughly  mix  the  water  and 
petroleum  ether,    which   causes  the   gum   held   in   solu- 
tion by  the  ether  to  precipitate,   and  on  refiltering  is 
retained.    The  second  ether  solution  that  has  been  cool- 
ing is  now  poured  on  to  the  filter  along  with  the  precipitate, 
rinsing    out    the  beaker  with  ice  cold  petroleum  ether. 
Treat  with  25  c.c.  of  ice  cold  water,  shaking  and  refiltering, 
as  described  above.     Repeat  this  operation  twice,  trans- 
fer the  filter,  and  precipitate  to  the  weighed  beaker,  and 
dry  in  the  hot  air  oven  at  105°  to  115°  C.  and  weigh. 


ANALYSIS  OF  OIL  VARNISHES.  211 

Increase  in  weight,  over  that  of  the  beaker,  stirring  rod 
and  filter,  represents  the  weight  of  the  gum. 

The  petroleum  ether  solution  containing  the  varnish 
oils  is  poured  into  a  weighed  beaker,  the  excess  of  petro- 
leum ether  evaporated  off  with  due  precautions,  and  the 
beaker  placed  in  the  hot  air  oven  for  3  hours  at  150°  C., 
cooled  and  weighed.  The  residue  represents  the  fixed 
oils  in  the  varnish. 

382.  Long  oil  varnishes.     Distil  ofT  the  thinners  from 
a  portion  of  the  sample.     Weigh  out  10  grams  of  the 
gum  and  oil  into  a  weighed  beaker  as  described  above, 
cool  down  below  15°  C.  and  add  50  c.c.  of  petroleum  ether 
cooled  below  0°  C.     Set  in  the  freezing  mixture  for  an 
hour  and  finish  exactly  as  described  under  short  oil  var- 
nishes.   The  separation  of  the  total  gum  in  long  oil  var- 
nishes is  quite  difficult  and  requires  considerable  patience 
and    experience.    According    to    the    experience    of    the 
author,  Scott's  method  gives  somewhat  low  results,  espe- 
cially as  rosin  is  quite  soluble  in  cold  petroleum  ether. 

383.  Determination     of    the     so-called     insoluble     and 
soluble  gums.    This  method  is  somewhat  similar  to  the 
above,  and,  in  the  hands  of  a  careful  chemist,  when  run 
alongside  of  standard  varnishes,  will  throw  considerable 
light  on  the  nature  of  the  sample  in  question. 

Weigh  2  grams  of  the  sample  into  a  weighed  6-oz.  wide- 
mouth  flask,  add  2  c.c.  of  chloroform,  100  c.c.  of  80° 
petroleum  ether,  gradually  and  with  constant  shaking  so 
as  to  avoid  any  preciptation,  until  15  c.c.  are  added, 
allow  to  stand  over  night.  The  precipitated  gums  adhere 
to  the  bottom  of  the  flask.  Decant  and  wash  with  a  little 
petroleum  ether.  Dry  to  constant  weight  as  insoluble 
gum. 

The  petroleum  ether  extract  should  be  decanted  into  a 
weighed  beaker,  the  petroleum  ether  evaporated  off  and 


212  ANALYSIS  OF  MIXED   PAINTS. 

the  beaker  dried  at  100°  for  seven  to  eight  days  to  con- 
stant weight.  All  linseed  oil  should  now  be  in  the  form 
of  linoxyn.  Digest  over  night  with  chloroform,  which 
will  dissolve  the  gum,  and  leave  the  linoxyn  undissolved. 
Filter  through  cotton  wool.  Evaporate  off  the  chloroform, 
dry  to  constant  weight  in  the  steam  oven  and  weigh  as 
soluble  gum. 

A  varnish  to  meet  with  the  requirements  of  the  United 
States  Treasury  Department,  among  other  things,  should 
contain  not  less  than  25  per  cent  of  best  quality  imported 
gums,  and  must  not  contain  rosin  or  petroleum  products. 

Varnishes  containing  wood  oil  are  liable  to  give  mis- 
leading results  by  the  above  method,  as  the  whole  or  a 
considerable  portion  of  the  wood  oil  will  be  precipitated  by 
the  petroleum  ether,  depending  on  the  length  of  time  and 
temperature  to  which  the  oil  has  been  heated. 

384.  Detection    and    estimation    of   rosin    in    varnishes. 
Qualitatively  rosin   may   be  detected   as   follows:    Pour 
about  5  c.c.  of  the  varnish  into  a  small  separatory  funnel, 
add  about  5  c.c.  of  carbon  bisulphide,  shake  and  add  10  c.c. 
of    acetic    anhydride.      Allow   to    stand    until   complete 
separation  takes  place.     Draw  off  the  lower  layer,  which 
is  the  acetic  anhydride.     Pour  1  or  2  c.c.  of  the  acetic 
anhydride  portion  into  an  inverted  crucible  cover,  add 
carefully,  by  means  of  a  stirring  rod,  one  drop  of  sulphuric 
acid    (34.7  c.c.  of  sulphuric  acid  to  35.7  c.c.   of  water) 
to  the  edge  of  the  cover,  so  that  it  will  mix  slowly  with 
the  acetic  anhydride,  if  rosin  is  present  a  characteristic 
fugitive  violet  color  will  result. 

385.  The  quantitative  estimation  of  rosin  in  the  pres- 
ence of  other  varnish  gums  is  a  problem  of  especial  diffi- 
culty.    Gill,1   suggests  a   method   based   on  comparative 
ester  values.    The   ester  value   being  obtained   by  sub- 

1  J.  Amer.  Chem.  Soc.  XXVIII.,  No.  12,  page  1723. 


ANALYSIS  OF  OIL   VARNISHES. 


213 


tracting  the  free  acid  value  from  the  saponification  value. 
The  gums  are  separated  from  the  oils  by  Twitchell's 
method,  the  last  traces  of  moisture  being  removed  by 
drying  over  sulphuric  acid.  Gill  obtains  the  following 
values  for  rosin  and  kauri. 


Gum. 

Saponifi- 
cation. 

Free 
Acids. 

Ester. 

Aver- 
age. 

Pure  rosin 

,  No.  1 

182.3 

160.1 

22.2 

Pure  rosin 

,  No.  6    .    . 

185.7 

161.7 

24.0 

23.1 

Kauri,  No 

.  1        ... 

124.2 

41.0 

83.2 

Kauri,  No 

.  2    .... 

129.7 

45.0 

84.7 

84.0 

By  the  use  of  the  usual  formula 

100  (7  -  n) 


x  = 


m  —  n 


the  percentage  of  adulteration  may  be  approximated,  as 
described  in  the  chapter  on  the  Analysis  of  the  Vehicle, 
in  discussing  cotton-seed  oil. 

387.  Gill's  method  is  open  to  considerable  criticism,  as 
he  directs  that  the  Free  Acid  Value  be  obtained  by  direct 
titration,  and  the  Saponification  Value  by  saponifying  in 
practically  an  open  flask.  Dietrich  l  has  shown  that  direct 
titration  gives  acid  values  far  too  low  for  all  resin,  because 
the  complete  neutralization  of  the  rosin  acid  proceeds 
slowly.  As  an  illustration  of  this  point,  Worstall  *  gives 
the  following  experiment: 

"  Several  portions  of  a  sample  of  Kauri,  whose  acid 
number  has  been  accurately  determined  as  103,  were 
weighed  out  arid  the  acid  number  determined  by  indirect 

1  Analyse  der  Harze,  Balsane,  und  Gumminharze. 

2  Chemical  Constants  of  Fossil  Resins,  J.  A.  Chem.  Soc.  XXV.,  page 
860. 


214 


ANALYSIS  OF  MIXED  PAINTS. 


titration  at  different  intervals  of  time, 
as  follows: 


The  results  were 


Time.  Acid  No. 

5  minutes 82 

1  hour 92 

3  hours 96 

6  hours 101 

12  hours 102 

18  hours 103 

388.  Regarding  open  saponification  Worstall  states 
that  "  from  the  researches  of  Tschirch  and  his  pupils,  it 
appears  that  the  copals  consist  of  '  resenes '  -  -  neutral 
compounds  containing  oxygen  and  possibly  of  an  aldehyde 
nature  —  and  of  the  resin  acids.  Other  investigators 
have  noted  the  fact  that  the  copals  will  absorb  oxygen, 
and  evidently  the  increase  in  acid  number  and  decrease  in 
iodine  absorption  is  due  to  the  oxidation  of  these  *  resenes/ 
by  contact  with  the  air,  to  resin  acids.  .  .  .  That  this 
increase  in  the  acid  number  is  actually  due  to  oxidation, 
the  following  experiments  will  illustrate : 

"A  number  of  samples  of  Kauri  were  selected,  each  one 
finely  powdered,  and  its  acid  and  iodine  numbers  deter- 
mined. These  samples  were  then  left  four  months  in 
open  bottles  exposed  to  the  air,  and  the  .powdered  resins 
stirred  from  time  to  time  to  promote  oxidation.  At  the 
end  of  this  time  their  constants  were  again  determined 
with  the  following  results. 


No. 

Before 
Acid. 

Oxidation 
Iodine. 

After 
Acid. 

Oxidation 
Iodine. 

Acid 
Increase. 

Iodine 
Decrease. 

1 

72 

154 

87 

133 

15 

21 

2 

76 

159 

111 

121 

35 

38 

3 

77 

140 

93 

115 

16 

25 

4 

72 

170 

107 

110 

35 

60 

5 

97 

109 

104 

99 

7 

0 

6 

105 

113 

109 

112 

4 

1 

ANALYSIS  OF  OIL  VARNISHES.  215 

"  Samples  1,  2,  3  and  4  were  hard,  '  bold  '  gum  of  highest 
quality,  while  samples  5  and  6  were  of  a  soft,  spongy, 
lowest  grade  Kauri,  in  which  oxidation  had  already  made 
much  progress  before  the  experiment  was  carried  out. 

"  This  oxidation  proceeds  rapidly  in  presence  of  alkalies, 
so  that  open  saponification  with  alcoholic  caustic  potash 
gives  acid  numbers  that  are  much  too  high.  Doubtless 
this  fact,  in  connection  with  the  impossibility  of  obtaining 
correct  acid  numbers  by  direct  titration,  has  led  to  the 
reporting  of  ester  values  in  resins  where  no  esters  exist. 
That  Kauri  is  free  from  esters  was  shown  by  saponifying 
several  samples  in  flasks  with  return  condensers,  digesting 
for  one  hour  on  the  steam  bath.  In  every  case  the  saponi- 
fication number  thus  found  was  the  same  as  the  indirect 
acid  number." 

389.  From  the  above  data  it  is  evident  that  in  order  to 
approximate  the  percentage  of  rosin  in  a  varnish  by  the 
so-called   ester   values   according   to   Gill's   method,  each 
analyst  must  establish  his  own  set  of  figures,  under  certain 
definite  working  conditions,  obtaining  his  data  from  var- 
nishes  of  known   composition.    Any   variation   of   these 
conditions,  either  in  time,  factor  or  condition  of  the  gums, 
is  certain  to  give  different  results. 

Little  that  is  reliable  has  been  written  concerning  the 
detection  of  the  other  varnish  gums.  Certain  resins,  how- 
ever, give  some  indication  of  their  presence.  For  instance, 
Kauri  imparts  a  reddish  stain  to  a  varnish.  Damar,  if 
present  in  considerable  quantity,  can  be  detected  by  its 
smell,  especially  in  the  dried  varnish.  It  is  seldom  found 
in  varnishes  intended  for  outside  use. 

390.  In  closing,  a  word  should  be  said  concerning  wood 
oil.    This  product,  the  properties  of  which  are  but  little 
understood  by  the  majority  of  chemists,  is  finding  a  wide 
use  among  varnish  manufacturers.     It  is  claimed  by  var- 


216  ANALYSIS  OF  MIXED  PAINTS. 

nish  manufacturers  that  by  the  use  of  wood  oil,  varnishes 
containing  a  large  amount  of  rosin  may  be  prepared,  pos- 
sessing satisfactory  wearing  qualities  and  free  from  the 
objectionable  features  of  ordinary  rosin  varnishes.  How- 
ever, in  light  of  the  rather  heavy  losses  encountered  by  a 
number  of  varnish  firms  in  endeavoring  to  prepare  a  satis- 
factory rosin-wood  oil  varnish,  the  above  claims  of  the 
varnish  manufacturers  may  be  questioned  somewhat.  As 
to  the  analysis  of  this  type  of  varnish  the  author  is  not 
aware  of  any  suitable  published  method.  It  is  said,  how- 
ever, that  it  may  be  detected  qualitatively  by  practical 
varnishers,  in  quantities  as  low  as  five  per  cent  by  the 
characteristic  odor  given  off  in  sandpapering  a  coat  which 
has  barely  dried. 

391.  Navy  specifications  for  interior  varnish  for  naval 
vessels,  1906.      To    be    of    the    best    quality  and  manu- 
facture and  equal  in  all  respects  —  including  body,  cov- 
ering   properties,   gloss,    finish   and    durability  —  to   the 
standard  samples  in  the  general  storekeeper's  office,  navy- 
yard,    New   York.     To    be    made   exclusively   from    the 
best  grade  of  hard  varnish  resins,  pure  linseed  oil,  pure 
spirits  of  turpentine  and  lead  manganese  driers,  and  to  be 
free  from  all  adulterants  or  other  foreign  materials.     The 
varnish  must  flash  above  105°  F.,  set  to  touch  in  from  6  to 
8  hours,  and  dry  hard  within  24  hours  in  a  temperature 
of  70°  F.    It  must  stand  rubbing  with  pumice  stone  and 
water  within  36  hours  without  sweating,  and  must  polish 
in  72  hours  with  rotten  stone  and  water.    To  be  as  clear 
and  not  darker  than  the  standard  sample,  and  to  be  equal 
to  it  in  all  respects  as  above  specified. 

392.  Navy  specifications  for  black   asphaltum  varnish, 
1906.     Black  asphaltum  varnish  must  be  of  pure,  high- 
grade  asphaltum  of  the  very  best  quality,  pure  linseed  oil, 
pure  spirits  of  turpentine  and  lead  manganese  driers,  and 


ANALYSIS  OF  OIL  VARNISHES.  217 

to  be  free  from  all  adulterants  or  other  foreign  materials, 
and  must  contain  not  less  than  20  gallons  of  prepared  lin- 
seed oil  to  100  gallons  of  varnish.  It  must  not  flash 
below  105°  F.  (open  tester).  It  must  mix  freely  with  raw 
linseed  oil  in  all  proportions;  must  be  clear  and  free  from 
sediment,  resin,  and  naphtha,  when  flowed  on  glass,  and 
allowed  to  drain  in  a  vertical  position;  the  film  must  be 
perfectly  smooth  and  of  full  body.  It  must  set  to  touch 
in  from  1J  to  2  hours,  and  dry  hard  in  less  than  20  hours 
at  70°  F.  When  dry  and  hard  it  must  not  rub  up  or  powder 
under  friction  by  the  finger.  The  application  of  heat  must 
quicken  the  time  of  drying  and  give  a  harder  film. 


CHAPTER  XX. 

THE  PRACTICAL  TESTING  OF  VARNISHES. 

393.  The  thorough  practical  testing  of  varnishes  is  an 
exceedingly  difficult  matter  for  the  average  chemist,  as  it 
requires  long  familiarity  with  the  direct  application  of 
varnishes  under  a  large  variety  of  circumstances  and  con- 
ditions.    However,  there  are  several  practical  tests  which 
can  be  made  without  special   difficulty,  and  which  will 
throw  considerable  light  on  the  character  of  the  varnish, 
especially  if  the  chemist  be  supplied  with  a  standard  set  of 
varnishes  which  he  can  run  along  with  the  sample  to  be 
tested,  and  have  constantly  by  him  to  enable  him  to  check 
up  his  judgment  by  comparison. 

394.  Smell.    The   smell   of   a   varnish   will   often  tell 
much  concerning  its  value.    A  good,  wholesome,  gummy 
odor  usually  indicates  a  varnish  made  from  good  materials, 
while  a  strong,  raw,  pungent  odor  is  often  the  sign  of  a 
cheaper  grade   of  goods.     Markedly  inferior   articles  can 
almost  witnout   exception    be   detected  in  this    manner. 
Occasionally  the  true  odor  of  the  varnish  is  masked  by  a 
strong  turpentine  odor,  in  which  case  allow  a  sample  of 
the  varnish  to  drain  out  of  a  beaker  for  3  to  5  minutes 
and  then  note  the  smell  of  the  portion  adhering  to  the  sides 
of  the  beaker,  i.e.,  the  "  after  smell,"  as  it  is  called. 

395.  Consistency.    The  consistency  of  a  varnish  is  to 
a  considerable  degree  regulated  according  to  the  work 
for  which  it  is  to  be  used,  and  should  be  judged  accord- 
ingly.    There  is  a  marked  tendency,  at  the  present  time, 
to  make  varnishes  altogether  too  thin.    This  may  in  part 

218 


THE    PRACTICAL    TESTING    OF    VARNISHES.        219 

be  due  to  the  insistent  demands  made  by  contractors  and 
other  varnish  users  for  goods  that  will  "  work  fast  "  and 
dry  quickly,  but  it  should  be  remembered  that  such 
varnishes  do  not  afford  the  measure  of  protection  to  the 
surface  that  is  regarded  necessary  by  the  best  practical 
users  of  varnish. 

396.  Working    and    flowing.     The    working    qualities 
of  the  varnish  under  the  brush  will  at  once  show  whether 
the  chemist  is  dealing  with  a  "  long  oil  "  or  a  "  short  oil " 
varnish.     A  test  board  having  been  suitably  surfaced  and 
filled  either  with  thin  shellac,  or  with  the  varnish  reduced 
with  25  per  cent  of    turpentine,  dried  and  sandpapered 
down  smooth,  is  given  an  even,  uniform  coat  of  the  varnish 
to  be  tested.     The  length  of  time  the  varnish  can  be  worked 
under  the  brush,  before  it  exerts  a  characteristic  "  pull  " 
on  the  brush,  is  indicative  of  the  character  of  the  varnish. 
If  it  permits  of  sufficient  time  for  thorough  brushing  out 
so  that  a  large  panel  could  be  coated  and  worked  out 
smooth,  before  it  begins  to  pull  on  the  brush,  i.e.,  "  set  up," 
the  sample  would  be  considered  a  long  oil  varnish,  while 
if  it  begins  to  pull  under  the  brush  almost  at  once,  it  would 
be  considered  a  short  oil  varnish.    Naturally,  there  are 
varnishes    which   do    not    exhibit  these    extremes,   but 
usually  the  classification  can  be  made  without  difficulty. 

397.  Special  notice  should  be  taken  of  the  way  the 
varnish  flows  out  into  a  uniform  surface,  whether  it  does 
so  \\ith  ease,  or  slowly  and  with  difficulty.     In  apply- 
ing the  final  coats  the  working  and  flowing  can  be  studied 
with  greater  exactness.     Some  varnishes  will  work  easily, 
others  will  work   "  tough,"   some   "  greasy,"   etc.;   with 
a  little  experience  the  chemist  can  grade  them  with  con- 
siderable accuracy.    As  mentioned  in  a  preceding  para- 
graph, there  are  many  varnishes  on  the  market  which  are 
altogether  too  thin.     Such  varnishes  will  work  and  flow 


220  ANALYSIS    OF    MIXED    PAINTS. 

with  great  ease  because  of  their  excessive  thinness,  and 
hence  the  consistency  must  be  taken  into  account  when 
passing  on  the  working  and  flowing  qualities. 

398.  Time  of  drying.     The  time   a  varnish  requires 
to  dry  properly,  i.e.,  to  harden  thoroughly,  is  regulated 
according  to  the  purpose  for  which  the  varnish  is  to  be  used. 
For  instance,  floor  varnishes  are  supposed  to  dry  hard  over 
night,  while  the  average  spar  varnish  will  require  a  much 
longer  time.     Hence  the  samples  tested  should  be  com- 
pared   with  the  accepted    standards  of  those    types  of 
varnishes,  both  on  the  wood  test  surface  and  on  a  sheet  of 
glass,  on  which  samples  of  the  varnishes  have  been  placed 
and  then  set  in  a  dust-free  but  unconfined  place  at  an  angle 
of  about  30  degrees  from  the  perpendicular.    The  best 
results  are  secured  by  resting  the  glass  on  a  couple  of  small 
hooks,  which  permits  the  varnish  to  drain  freely.    The 
rapidity  of  the  drying  should  be  noted  at  regular  intervals. 
When  dry,  the  tests  should  be  saved  for  further  examination. 

399.  The  sponge  test.    After  the  requisite   number  of 
coats  have  been  applied  to  the  test  boards  and  the  finish- 
ing coat  has  hardened  thoroughly,  a  sponge  made  of  several 
thicknesses  of  felt  is  thoroughly  moistened  and  laid  on  the 
varnished  surface  and  allowed  to  remain  for  a  stated  number 
of   hours,  undisturbed.     A  high-grade  varnish  will  either 
show  no  discoloration  at  all,  or  will  regain  its  color  on  dry- 
ing, provided,  of  course,  that  it  has  been  suitably  applied. 
A  varnish  containing  a  large  amount  of  rosin  will  be  more 
or  less  badly  corroded  and  will  remain  permanently  white 
and  discolored.     With  a  little  practice  by  working  with 
varnishes  of  known  composition  the  chemist  can  make  a 
pretty  shrewd  guess  as  to  the  approximate  amount  of  rosin 
present  by  the  degree  of  discoloration.    Right  here  the 
author  wishes  to  state  that  the  use  of  cheap  inferior  rosin 
varnishes  has  caused  untold  damage.    There  is  probably 


THE    PRACTICAL    TESTING    OF    VARNISHES  221 

more  rosin  varnish  sold  than  all  other  grades  put  together. 
It  is  claimed  by  high-class  manufacturers  that  the  addition 
of  three  or  four  per  cent  of  hardened  rosin  will  enable  the 
varnish  maker  to  melt  his  gums  at  a  somewhat  lower  heat 
and  without  darkening,  thus  making  a  better  and  lighter- 
colored  varnish;  but  the  addition  of  rosin  has  passed  this 
point  so  far  that  a  three  or  four  per  cent  addition  is  a  very 
minor  consideration  indeed. 

400.  Another  modification  of  the  above  test  is  to  varnish 
a  clean  strip  of  tin,  and  after  thorough  drying  immerse  it 
under  water  and  note  the  rapidity  and  extent  of  corrosion 
and  discoloration. 

401.  Toughness  and  elasticity.     In  order  for  a  varnish 
to  be  durable  and  give  entire  satisfaction,  it  must  have  the 
desired  toughness  and  elasticity  as  well  as  the  requisite 
hardness.     A  varnish  which  is  brittle,  although  it  may  have 
the  required  hardness,  will  be  easily  cracked  or  crushed  by 
a  very  moderate  blow.    Some  varnishes  are  required  to  be 
tougher  and  more  elastic  than  others,  as  in  the  case  of 
floor  finishes. 

402.  The  varnish  having  thoroughly  dried  on  the  test 
glass  alongside  of  the  standard  sample,  its  toughness  may 
be  determined  to  a  certain  extent  by  its  behavior  under  the 
thumb-nail,  and  the  results  obtained  compared  with  a 
similar  examination  on  the  varnished  test  board.    Also  the 
films  of  the  thoroughly  dried  varnish  on  the  test  glass  may 
then   be  scratched   with   a   sharp  instrument.     A   small, 
sharply  pointed  knife-blade  is  excellent  for  this  purpose. 
A  first-class  varnish  having  suitable  toughness  and  elasticity 
will  show  a  smooth,  even  scratch,  no  scaling  or  "  dusting  " 
being  observable ;  and  if  the  knife  be  held  in  the  proper 
position,  a  small  uniform,  coherent  ribbon  of  varnish  will 
be  ploughed  off.     If  the  varnish  is  deficient  in  elasticity 
and  toughness,  it  will  scale    away  under  the  knife-point, 


222  ANALYSIS    OF    MIXED    PAINTS 

exhibiting  a  ragged,  irregular  scratch.  Varnish  films  con- 
taining rosin  when  tested  with  the  knife-point  will  usually 
"  dust  "  more  or  less  badly,  i.e.,  fly  away  from  the  knife- 
point in  the  form  of  a  fine  powder,  settling  on  the  glass  at 
a  considerable  distance  from  the  scratch.  The  fact  that 
varnishes  vary  greatly  in  consistency  should  be  taken  into 
account  in  making  these  tests,  as  the  films  on  the  glass  will 
vary  in  thickness  according  to  the  consistency  of  the 
varnish. 

403.  In   judging   the    brittleness   of   a  varnish   on  a 
test  board,  especially  if  it  is  hard  wood,  the  effect  of  the 
material  used  for  the  first  coat  must  be  taken  into  con- 
sideration.   This  may  be  readily  shown  by  taking  a  hard- 
wood board,  coating  a  portion  of  it  with  shellac,  another 
portion  with  an  average  cheap  liquid  filler,  and  the  remain- 
ing portion  with  the  varnish  itself.    After  applying  two 
coats  of  varnish  over  the  entire  surface  and  allowing  it  to 
harden  thoroughly,  it  will  be  found  on  testing  the  surface 
with  a  knife  that  the  varnish  over  the  liquid  filler  is  very 
brittle,  that  over  the  shellac  somewhat  brittle,  while  the 
straight  varnish-filled  surface  will  remain  tough  and  elastic. 
Another  method  of  testing  the  elasticity,  is  to  varnish 
a  strip  of  tin,  and,  after  thorough  drying,  bend  the  tin 
and  note  the  extent  which  the  varnish  gives  under  the 
strain  to  which  it  is  subjected.     In  making  these  various 
tests,  the  chemist  must  be  certain  that  the  varnish  is 
thoroughly  dry,  as  many  of  the  cheaper  varnishes  harden 
slowly,  and,  if  examined  too  soon,  will  show  greater  tough- 
ness and  elasticity  than  would  be  obtained  in  actual  practice. 

404.  Hardness,     A  varnish  may  have  the  toughness  and 
elasticity  required  of  first-class  goods,  but  may  be  deficient 
in  hardness.     In  order  to  report  on  the  hardness,  the 
chemist  should  have  some  means  of  giving  this  quality  a 
numerical  value.     An  instrument  for  this  purpose  has  been 


THE    PRACTICAL    TESTING    OF    VARNISHES  223 

devised  by  Dr.  A.  P.  Laurie  and  F.  G.  Baily  of  Heriot  Watt 
College,  Edinburgh,  the  essential  features  of  which  are  a 
central  rod  sliding  easily  in  a  vertical  direction  through 
holes  in  two  brackets.  The  upper  portion  of  the  rod  has  a 
screw  thread,  on  which  is  a  running  nut.  By  means  of  a 
milled  head  at  the  top  the  rod  is  twisted  round,  and  the  nut 
caused  to  travel  up  and  down  on  the  thread.  A  spring  is 
attached  at  its  upper  end  to  the  travelling  nut  and  at  the 
lower  end  to  the  lower  bracket.  To  the  lower  end  of 
the  rod"  is  attached  a  hardened  blunt  steel  point,  and  the 
varnished  plate  to  be  tested  is  placed  under  this  point,  and 
the  point  brought  to  the  surface  of  the  varnish.  The  test 
surface  is  drawn  slowly  under  the  point,  the  pressure  being 
increased  until  a  white  scratch  is  observed,  at  which 
point  the  reading  is  noted  on  the  scale.  The  machine 
reads  to  a  maximum  of  2000  grams.  Spirit  varnishes 
break  down  at  a  pressure  of  about  100  grams,  rosin  varnishes 
200  to  400  grams,  fairly  good  common  varnishes  at  about 
700  grams,  and  fine  carriage  varnishes  at  1200  grams  and 
upwards.  The  inventors  claim  that  the  best  oil  varnishes 
take  twelve  months  to  reach  their  maximum  hardness,  and 
that  the  rate  of  drying  and  the  ultimate  hardness  can  be 
measured  with  accuracy  by  their  instrument. 

405.  Classification  of  varnishes.     The  varnish  industry 
has  from  its  beginning  been  conducted  with  as  much  secrecy 
as  possible,  and  but  little  has  been  published  that  would 
enable  the  average  chemist  to  pass  judgment  on  the  different 
grades  and  varieties  of  varnish,  and  for  this  reason  a  short 
discussion  of  some  of  the  principal  classes  of  varnish  may 
not  be  amiss. 

406.  Floor  varnishes.  x  Goods  of  this  class  should  have 
a  medium  consistency.     If  heavy  they  will  require  a  longer 
time  to  dry  and  harden  than  is  desirable,  and  would  be  apt 
to  become  marred  from  usage  before  thoroughly  hardened; 


224  ANALYSIS    OF    MIXED  PAINTS. 

if  too  thin  they  will  not  afford  the  desired  protection  to  the 
wood.  In  price  they  are  about  the  same  as  for  first-class 
interior  varnishes,  ranging  usually  from  $2.00  to  $2.50  per 
gallon  wholesale.  Floor  varnishes  are  usually  "  long  oil  " 
goods,  as  a  high  degree  of  elasticity  is  required. 

407.  Interior  varnishes.     Varnishes    for  interior  work 
should  be  of  fairly  heavy  consistency,  so  as  to  stand  rubbing. 
For  the  best  class  of  work  they  should  be  "  long  oil," 
although  "  short  oil  "  goods  may  be  used  for  the  under- 
coats.    In  price  they  usually  range  from  $2.00  to  $2.50  per 
gallon  wholesale.     Often,  especially  in  contract  work, "  No. 
1  Coach  "  goods  are  used.    This  term  means  absolutely 
nothing,  as  it  stands  for  no  specific  grade  or  quality  of 
varnish.     Sold  under  this  name  varnishes  are  put  on  the 
market  for  $0.90  to  $1.10  per  gallon,  or  even  less,  and  are 
usually  high  in  rosin  and  benzine  or  heavier  petroleum- 
products.     Polishing  varnishes,  such  as  are  used  for  pianos, 
high-class  furniture,  etc.,  are  usually  of  excellent  quality, 
averaging  in  price  from  $2.50  to  $2.75,  although  the  very 
best  grades  may  run  as  high  as  $3.50  wholesale. 

408.  Interior  varnishes  being  subjected  to  less  strenuous 
usage  than  floor  finishes,  carriage  or  exterior  goods,  the 
tendency  has  been  to  lower  the  standard  of  quality,  until 
perhaps  low  grade,  inferior  goods  are  the  rule,  and  really 
high-grade  finishes  the  exception,  on  the  market  at    the 
present  time.     Neither  is  the  size  of  the  company  any 
guarantee  that  the  product  is  of  high  value,  for  many  of 
the  best  grades  of  varnishes  are  made  by  small  concerns 
who  depend  on  the  quality  of  their  goods  rather  than  on 
extensive  advertising  for  their  sales. 

409.  Exterior    varnishes.     These    should    always    be 
"  long  oil  "  goods.     Spar  varnishes,  which  are  the  usual 
type  of  exterior  varnishes,  should  be  of  medium  consistency, 
tough  and  elastic,  and  not  easily  scratched.     In  price  they 


THE    PRACTICAL    TESTING    OF    VARNISHES.        225 

usually  range  from  $3.00  to  $3.75  per  gallon  wholesale. 
Carriage  varnishes  bring  the  highest  price  of  all  varnishes, 
and  their  successful  manufacture  is  accomplished  by  only 
a  comparatively  small  number  of  concerns,  and  but  few 
domestic  brands  are  rated  equal  to  the  best  imported 
English  goods.  Domestic  carriage  varnishes  range  from 
$4.75  to  $5.75  wholesale,  and  the  best  imported  English 
goods  at  about  $7.25  per  gallon. 

410.  Short  volume.  It  is  a  lamentable  fact  that 
varnish  manufacturers  almost  invariably  defraud  the 
consumer  by  putting  out  their  packages  short  in  volume. 
Of  eleven  samples  purchased  by  the  author  on  the  open 
market,  in  the  original  package  none  were  full  measure. 
The  amount  of  shortage  is  given  in  the  following  table : 


No. 

Description. 

Per  Cent  Short- 
age of  Contents. 

1 

Floor  Varnish 

3  2 

2 

Floor  Varnish 

4  2 

3 

Floor  Varnish                  .        

2  1 

4 

Interior  Varnish                  

3  2 

5 

Exterior  Varnish     

2  1 

6 

Coach  Varnish     

2.1 

7 

Interior  Varnish      

8.4 

8 

Floor  Varnish 

3  2 

9 

Exterior  Varnish 

4  2 

16 

Floor  Varnish 

9  5 

18 

Floor  Varnish 

13  3 

Average    .    .        ...            ... 

5.0 

Five  per  cent  shortage  in  measure  represents  a  very  fair 
profit  to  the  manufacturer  in  itself. 

411.  Significance  of  lime  in  varnishes.  The  addition 
of  five  to  six  per  cent  of  quicklime  to  melted  rosin  makes 
it  considerably  harder.  The  compound  formed  easily 
dissolves  in  linseed  oil  (at  the  present  time  wood  oil  is 
largely  used),  and  when  properly  thinned  forms  the  base 
of  about  all  the  cheap  varnishes  on  the  market.  Such 


226 


ANALYSIS    OF    MIXED    PAINTS. 


varnishes  are  characterized  by  giving  a  brilliant  surface, 
easily  scratched,  and  in  a  short  time  liable  to  crack  badly. 
The  relation  between  the  percentage  of  lime  (CaO)  in  the 
varnish  and  its  toughness  and  elasticity  is  not  marked 
enough  to  enable  the  chemist  to  pass  judgment  on  its 
working  qualities  from  the  amount  of  lime  it  contains. 

412.  Sixteen  of  the  leading  varnishes  on  the  market 
were  tested  out  for  toughness  and  elasticity,  and  then  the 
amount  of  calcium  oxide  determined  in  each,  the  results 
obtained  being  given  in  the  following  table. 


No. 

Kind. 

Per  Cent 
of  Calcium 
Oxide  in 
Varnish. 

Elasticity  and 
Toughness. 

2 

Floor  Varnish 

0  868 

Good 

3 

Floor  Varnish 

0  246 

Good 

4 

Interior  Varnish   

0.200 

Good 

5 
6 

7 
9 

Exterior  and  Interior  Varnish 
No.  1  Coach  Varnish    .    .    .' 
Interior      
Exterior     

0.178 
0.313 
0.195 

Medium 
Good 
Poor 
Medium 

11 
13 

No.  1  Coach  Varnish   .    .    . 
Interior  Varnish               .    . 

0.265 
0.271 

Poor 
Very  Poor 

14 

Interior  Varnish       .... 

0.161 

Poor 

15 

0.800 

Medium 

17 

0.158 

Medium 

19 

Interior  Varnish       .... 

0.158 

Good 

21 

Interior  Varnish   

0.212 

Good 

23 
25 

Interior  Coach  Varnish    .    . 
Interior  Varnish    

0.532 
0.281 

Poor 
Poor 

413.  Of  twelve  brands  of  floor  varnishes  examined  by 
the  author,  four  were  altogether  too  thin  for  the  purpose 
intended;  and  of  fourteen  interior  finishes,  four  were  ex- 
ceedingly thin,  and  several  of  the  remainder  were  below 
average  in  this  respect. 

Of  a  total  of  twenty-six  of  the  leading  brands  of  floor, 
exterior  and  interior  varnishes  tested  out  by  the  author, 
seven  were  considered  first  class  in  all  respects,  eight  were 
medium  or  just  fair  quality,  while  eleven  were  unquestion- 


THE   PRACTICAL  TESTING  OF  VARNISHES.          227 

ably  poor  and  inferior  both  as  regards  working  and  the 
quality  of  the  film  after  drying.  Of  the  above  eleven, 
eight  were  interior  finishes. 

414.  The  twenty-six  with  but  two  exceptions  flashed  at 
room  temperature,  a  fact  which  is  worthy  of  considerable 
attention  on  the  part  of  the  consuming  public  as  regards 
fire  risk. 


228 


ANALYSIS  OF  MIXED   PAINTS. 


APPENDIX. 


415.  TRADE  NAMES  OF  THE  PRINCIPAL  PAINT  PIGMENTS 
WITH  CHEMICAL  NAMES. 


BLUE  PIGMENTS. 


Trade  Name. 


Composition. 


Antwerp  blue 
Chinese  blue 
Cobalt  blue  . 


Prussian  blue 
Ultramarine 


Potassium  ferric  ferrocyanide. 

tt  u  «' 

A  compound  of   the   oxides   of   alumina 

and  cobalt. 

Potassium  ferric  ferrocyanide. 
Exact  constitution  unknown. 


RED  AND  YELLOW  PIGMENTS. 


Trade  Name. 


Composition. 


American  vermilion 

Chinese  vermilion    . 
Chrome  yellow     .    . 

English  vermilion    . 
Indian  red        .    .    . 


Litharge 

Lemon  chrome     .    . 

Ochre        

Orange  chrome    .    . 
Para  vermilion     .    . 
Permanent  vermilion 
Radium  vermilion  . 
Tuscan  red    .... 


Venetian  red 


Usually  basic  chromate  of  lead,  sometimes 

an  cosine  vermilionette  on  red  lead. 
Sulphide  of  mercury. 
Lead  chromate  usually  containing  lead 

sulphate. 

Sulphide  of  mercury. 
Natural  oxide  of  iron  about  90  per  cent 

or  more,  pure. 
Lead  monoxide. 
Usually  a  mixture  of  lead  chromate  and 

lead  sulphate. 
Earthy  base  carrying  about  20  per  cent 

hydrated  ferric  oxide. 
Lead  chromate. 
An  organic  red  precipitated  on  an  inert 

base. 

Red  lead  coated  with  organic  color. 
A   more   or  less   impure   oxide   of   iron 

brightened  with  organic  color. 
Usually  a  mixture  of  oxide  of  iron  and 

calcium  sulphate. 


APPENDIX. 

WHITE  PIGMENTS. 


229 


Trade  Name. 

Composition. 

Barytes     

Barium  sulphate. 

Blanc  fixe     

Precipitated  barium  sulphate 

China  clay    
Corroded  lead  

Hydrated  silicate  of  aluminum. 
Basic  lead  carbonate 

English  white  
Gypsum     
Lithopone 

Calcium  carbonate. 
Hydrated  calcium  sulphate. 
A  combination  of  barium  sulphate    zinc 

Magnesite 

oxide  and  zinc  sulphide. 
Magnesium  carbonate 

Marble  dust 

Calcium  carbonate 

Paris  white 

Calcium  carbonate 

Ponolith    .    . 
Silex 

Similar  to  lithopone. 
Silica 

Silicate  of  magnesia    .    .    . 

Silver  white      
Spanish  white  .            ... 

Magnesium  silicate,  aluminum,  and  cal- 
cium are  usually  present. 
Silica. 
Calcium  carbonate 

Standard  zinc  lead  white    . 
Sublimed  white  lead   .    .    . 
Terra  alba  

Lead  sulphate  and  zinc  oxide  in  about 
equal  amounts. 
Apparently  a  basic  sulphate  of  lead  with 
about  5  per  cent  zinc  oxide. 
Hydrated  calcium  sulphate. 

White  lead    

Basic  carbonate  of  lead. 

Whiting        
White  mineral  primer     .    . 
White  ochre 

Calcium  carbonate. 
Calcium  carbonate. 
Calcium  carbonate 

Wood  filler    
Zinc  white 

Silica. 
Zinc  oxide 

Zinc  oxide  (leaded)     .    .    . 

Zinc  oxide  containing  a  varying  amount  of 
lead  sulphate. 

I 

ILACK  PIGMENTS. 

Trade  Name. 

Composition. 

American  gas  black    .    .    . 
Animal  charcoal          .    .    . 
Bone  black 

Very  nearly  pure  carbon. 
Carbon  and  calcium  phosphate. 
Carbon  and  calcium  phosphate 

Drop  black 

Carbon  and  varying  amount  of  ash 

Frankfort  black 

Carbon  and  varying  amount  of  ash 

Graphite   
Hydrocarbon  black     .    .    . 
Ivory  black 

Natural  carbon  and  mineral  ash. 
Very  nearly  pure  carbon. 
Carbon    calcium  and  magnesium  phos- 

Lampblack        
Mineral  black  . 

phate. 
Very  nearly  pure  carbon. 
Ground  slate 

230 


ANALYSIS    OF    MIXED     PAINTS. 

GREEN  PIGMENTS. 


Trade  Name. 


Composition. 


Brunswick  green 
Chrome  green 
Emerald  green 


Usually  Prussian  blue  and  chrome  yel- 
low on  an  inert  base. 
Aceto-arsenite  of  copper. 


416.  ATOMIC  WEIGHTS  OF  THE  MORE  COMMON  ELEMENTS. 


0=  16. 


Atomic 
Weight. 


Symbol. 


Aluminum 27.1 

Antimony 120.2 

Arsenic 75.0 

Barium 137.4 

Bromine 79.96 

Cadmium 112.4 

Calcium 40.1 

Carbon 12.0 

Chlorine        35.45 

Chromium 52 . 1 

Cobalt 59.0 

Copper      63.6 

Hydrogen 1.008 

Iodine 126.85 

Iron 55.9 

Lead 206.9 

Magnesium 24.36 

Manganese 55.0 

Mercury        200.0 

Molybdenum 96.0 

Nitrogen       14.04 

Oxygen : 16.0 

Phosphorus      31.0 

Platinum      194.8 

Potassium 39.15 

Silicon 28.4 

Silver    .    . 107.93 

Sodium 23.05 

Sulphur 32.06 

Zinc  .  65.4 


Al 

Sb 

As 

Ba 

Br 

Cd 

Ca 

C 

Cl 

Cr 

Co 

Cu 

H 

I 

Fe 

Pb 

Mg 

Mn 

Hg 

Mo 

N 

O 

P 

Pt 

K 

Si 

Ag 

Na 

S 

Zn 


APPENDIX.  231 

417.    FACTORS    FOR  GRAVIMETRIC  ANALYSIS. 


Determined  as. 

Required. 

Factor. 

A1203 

Al 

0.5303 

As2S3 

As 

0.6093 

As2S3 

As203 

0.8043 

Mg2As207 

As203 

0.6372 

BaSO4 

Ba 

0.5885 

BaSO4 

PbSO4 

1.3004 

BaS04 

CaS04 

0.5837 

BaS04 

CaS042H20 

0.7382 

BaSO4 

S03 

0.3433 

BaSO4 

SO2 

0.2747 

CaO 

Ca 

0.7143 

CaO 

CaCO3 

1.784 

CaCO3 
CaO 

CO2 
CaSO42H2O 

0.440 
3.0715 

CaSO42H2O 
C02 
Cr203 

S03 
2PbC03Pb(OH)2 
PbCr04 

0.4561 

8.8068 
4.2288 

Cr2O3 

CrO3 

1.3137 

Cr203 

PbCrO4PbO 

7.1438 

Fe03 

Fe 

0.7000 

JtVoOV/^ 

K 

0.4491 

K2PtCL 

K 

0.1612 

K2PtClr 

M&PA 

K20 
Mg 

0.1941 
0.2188 

Mg2P207 

MgO 

0.3624 

Mg2P2O7 

MgC03 

0.7575 

Na-jSO, 

Na 

0.3243 

Na2SO4 
Pb§04 

Na20 
Pb 

0.4368 
0.6832 

PbS04 

PbO 

0.7359 

PbS04 
PbSO4 

Pb,04 
2PbC03Pb(OH)2 

0.7536 
0.8526 

PbSO4 

PbCrO4 

1.0676 

sof2°7 

Pf>SO4 

0.6376 

3.788 

Zn3 

ZnSO4 

2.478 

Zn 

ZnO 

1.2462 

ZnS04 

ZnO 

0.503 

232 


ANALYSIS    OF    MIXED    PAINTS. 


418.   MEASURES,  WEIGHTS   AND  TEMPERATURES. 


One  Imperial  gallon 

One  wine  gallon 

One  wine  gallon 

One  wine  gallon 

One  quart 

One  quart 

One  liter 

One  cubic  foot 

One  cubic  inch 

One  cubic  centimeter 

One  pound  Avoirdupois 

One  ounce  Avoirdupois 

One  gram 

One  inch 

One  foot 

One  yard 

One  meter 


277 . 27  cubic  inches. 
231 . 0  cubic  inches. 
3. 7854  liters. 

8.3389  pounds  water  at  40  C. 
57 . 88  cubic  inches. 

.  9464  liter. 
1 . 0567  quart. 
28315  cubic  centimeters. 
16.38  cubic  centimeters. 

.061  cubic  inch. 
453 . 6  grams. 
28.35  grams. 
15. 432  grains. 
.0254  meter. 
.3048  meter.  ^.. 

.91438  meter. 
39. 3708  inches. 


Fahrenheit  degrees 
Centigrade  degrees 


9  C.°  +  32 

5 

5  (F.°  -  32) 
9 


INDEX. 


Atomic  weights,  230. 

Benzine,  67. 

Black  pigments,  analysis  of,  145. 

Analysis  of  paints  tinted  with, 
149. 

Composition  of,  143. 

Specifications  for,  147. 

Typical  analyses  of,  148. 

Blue  paints,  composition  of,  33. 
Blue  pigments,  169. 

Analysis  of  cobalt  blue,  164. 

Analysis  of  blue  mixed  paints, 
161. 

Analysis  of  Prussian  blues,  159. 

Typical  analyses  of,  161,  164. 

Analysis  of  ultramarine,  162. 
Brown  paints,  composition  of,  34. 

Calcium  carbonate  pigments,  analy- 
sis of,  93. 

Cheapened  mixed  paints,  130. 
Chinese  blue,  169,  186. 
Chrome  green,  analysis  of,  176. 

Typical  analyses  of,  179. 
Chrome  leads,  analysis  of,  166. 

Analysis  of  paints    containing, 
169. 

Composition  of,  166. 

Typical  analyses,  169. 
Chrome  yellow,  analysis  of,  166. 
Clays,  analysis  of,  96. 

Typical  analyses  of,  100. 
Composition  of  colored  paints,  32. 
Comparison  of  paints  for  covering 

power,  103. 
Corn  oil,  44. 


Cottonseed  oil,  43. 
Crimson  red  lake,  186. 
Covered  testers,  64. 

Damar  varnish,  204. 

Specifications  for,  204. 
Driers,  188. 

Determination  of  lead  in,  189. 
of  manganese  in,  189. 
of  volatile  oils  in,  190. 
of  zinc  in,  190. 

Practical  tests,  191. 

Rosin  in,  191. 

Separation  of  benzine   and  tur- 
pentine, 190. 

Emerald  green,  179. 
Analysis  of,  179. 
Typical  analyses,  of,  181,  183. 
Estimation  of  petroleum  products, 

49. 
Estimation  of  rosin  in  .linseed  and 

mineral  oils,  60. 
Evaporation  test,  63. 

Factors,  231. 

Free  fatty  acids,  61. 

Fineness  of  pigments,  102. 

Fire  test,  66. 

Fish  oil,  44. 

Flash  point,  64. 

Gasoline,  68. 

Gravity   and  volume  of  pigments, 

106. 

Gray  paints,  composition  of,  35. 
Green  paints,  composition  of,  34. 


233 


234 


INDEX. 


Indian  reds,  analysis  of,  135. 
Inside  paints,  129. 
Iodine  number,  194. 

Determination  of,  54,  194. 

of  oils,  56, 

Preparation  of  reagents  for,  54. 
Iron  oxides,  analysis  of,  136. 

Analysis  of  paints    containing, 
149. 

Specifications  for,  142. 

Typical  analyses  of,  139,  141. 

Kerosene,  67. 

Labels  that  mislead,  19. 
Leaded-zinc  paints,  129. 
Linseed  oil,  39. 

Determination  of  flash  point  of, 
62. 

Extraction  from  paint,  39. 

From  inferior  seed,  45. 

Specifications  for,  47,  66. 

Tests  for  purity  of,  40. 
Lithographic  varnish,  67. 
Lithopone,  92. 

Mcllhiney's  method,  56. 
Mineral  oils,  41. 

N.  D.  Paint  law,  6. 

Ochers,  analysis  of,  135. 

Oils,  specifications  for,  66. 

Oil  varnishes,  analysis  of,  206. 

Classification  of,  223. 

Consistency  of,  218. 

Determination   of    soluble    and 
insoluble  gums  in,  211. 

Drying  of,  220. 

Estimation  of  rosin  in,  212. 

Hardness  of,  222. 

Long  oil,  211. 

Separation  of  rosin  gums,  208, 

209. 
of  volatile  oils,  207. 

Short  oil,  210. 


Oil  varnishes  —  continued. 

Short  volume  of,  225. 

Smell,  218. 

Specifications  for,  216. 

Specific  gravity,  207. 

Sponge  test,  220. 

Toughness  and  elasticity,  221. 

Viscosity,  207. 

Working  and  flowing,  219. 
Open  testers,  66. 

Paints,  107. 

Application  of  middle  coat,  115. 
of  paste  leads,  116. 
of  priming  coat,  112. 
of  third  coat,  115. 

Driers  in,  117. 

Oil  reductions  in,  113. 

Testing  of,  107. 

Test  structures  for,  107. 

Turpentine  reductions,  113. 
Para  iiitroaniline  lake,  184. 
Paris  green,  179. 
Paris  white,  93. 
Paste  wood  filler,  100. 
Ponolith,  92. 
Preparation  of  samples,  29. 

Ratio  of  pigment  to  vehicle,  31. 

Red  lead,  175. 

Red  oxides,  135. 

Red  paints,  composition  of,  32. 

Relation  of  lead  to  zinc,  24. 

Rosin  and  rosin  oils,  44. 

Saponification  value,  62. 
Separation    of    mineral    oil    from 

rosin  oil,  42. 

Separation    of  vehicle    from    pig- 
ment, 29. 
Shellac,  194. 

Detection  of  rosin  in,  194. 
Estimation  of  rosin  in,  194. 
Iodine  numbers  of,  196. 


INDEX. 


235 


Shellac  varnish,  196. 

Body  of,  197. 

Brewer's  test,  203. 

Composition  of,  196. 

Detection  of  benzine  in,  198. 

Determination  of  strength  of  al- 
cohol used,  197. 

Estimation  of  rosin,  202. 

Estimation  of  wood  alcohol  in, 
199. 

Maunhardt's  method  for  rosin, 
203. 

Typical  analyses  of,  204. 
Short  measure  and  weights,  24. 
Silica,  analysis  of,  96. 
Sublimed  lead,  analysis  of,  81. 

Composition  of,  82. 

Identification  and  estimation  in 
mixtures,  83. 

Paints,  128. 

Specific  gravity  of  oils,  40. 
Spot  test,  41. 

Table  of  atomic  weights,  230. 
Tinting  strength  of  colors,  104. 
Trade  names  of  pigments,  228. 

Ultramarine,  162. 

Umbers  and  siennas,  analysis  of, 

152. 
Analysis  of    paints   containing, 

158. 
Typical  analyses  of,  157. 

Vandyke-brown,  152. 
Venetian  red,  analysis  of,  135. 
Vermilion,  analysis  of,  170. 
Antimony  vermilion,  174. 


Vermilion  —  continued. 

Detection  of  vennilionettes,  171. 

Properties  of,  170. 

Typical  analyses,  174. 
Volatile  oils,  estimation  of,  39,  49. 

Excessive  use  of,  62. 

Identification  of,  48. 

Water,  detection  in  paint,  36. 

Estimation  of,  37. 

Occurrence  in  paints,  36. 
White  lead,  acetic  acid  in,  78. 

Color  of,  69. 

Estimation  of  carbon  dioxide  in, 
70. 

Foreign  pigments  in,  70. 

Lead  acetate  in,  69. 

Opacity  of,  69. 

Painting  tests  with,  69. 

Sandy  lead,  69. 

Short  weights,  79. 

Typical  analyses  of,  78,  79. 
White  mineral  primer,  93. 
White  ocher,  93. 
White  paints,  119. 

Analyses  of,  125,  128. 

Cost  of,  126. 

Qualitative  analysis  of,  119. 

Quantitative    analysis   of,    120, 

131. 
Why  paints  fail,  1. 

Yellow  paints,  composition  of,  33. 

Zinc  oxides,  analysis  of,  84. 
Classification  of,  86. 
Arsenic  and  antimony  in,  88. 
Typical  analyses,  87. 


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Arnold's  Compendium  of  Chemistry.     (Mandel.) Small  8vo,  3  50 

Austen's  Notes  for  Chemical  Students i2mo,  i  50 

Beard '  s  Mine  Gases  and  Explosions .     (In  Press. ) 

Bernadou's  Smokeless  Powder. — Nitro-cellulose,  and  Theory  of  the  Cellulose 

Molecule i2mo ,  2  50 

Bolduan's  Immune  Sera I2mo ,  i  50 

*  Browning's  Introduction  to  the  Rarer  Elements 8vo,  i  50 

Brush  and  Penfield's  Manual  of  Determinative  Mineralogy 8vo,  4  oo 

*  Claassen's  Beet-sugar  Manufacture.     (Hall  and  Rolfe.) 8vo,  3  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.    (Boltwood.).  .8vo,  3  oo 

Cohn's  Indicators  and  Test-papers i2mo,  2  oo 

Tests  and  Reagents 8vo,  3  oo 

Crafts's  Short  Course  in  Qualitative  Chemical  Analysis.   (Schaeffer.). .  .lamo,  i  50 

*  Danneel's  Electrochemistry.     (Merriam.) i2mo,  i   25 

Dolezalek's  Theory  of  the   Lead  Accumulator   (Storage   Battery).        (Von 

Ende,) i2mo,  2  50 

Drechsel's  Chemical  Reactions.     (Merrill.) i2mo,  i  25 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess.) 8vo,  4  oo 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Effront's  Enzymes  and  their  Applications.     (Prescott.) 8vo,  3  oo 

Erdmann's  Introduction  to  Chemical  Preparations.     (Dunlap.) 12010,  i   25 

*  Fischer's  Physiology  of  Alimentation Large  I2mo.,  2  oo 

Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

121110,  morocco,  i  50 

Fowler's  Sewage  Works  Analyses v I2mo,  2  oo 

Fresenius's  Manual  of  Qualitative  Chemical  Analysis.     (Wells.) .8vo,  5  oo 

Manual  of  Qualitative  Chemical  Analysis.  Part  I.  Descriptive.  (Wells.)  8vo,  3  oo 

Quantitative  Chemical  Analysis.    (Cohn.)     2  vols 8vo,  12  50 

Fuertes's  Water  and  Public  Health -.  .  i2mo,  i  50 

Furman's  Manual  of  Practical  Assaying 8vo,  3  oo 

*  Getman's  Exercises  in  Physical  Chemistry I2mo,  2  oo 

Gill's  Gas  and  Fuel  Analysis  for  Engineers. i2mo,  i  25 

*  Gooch  and  Browning's  Outlines  of  Qualitative  Chemical  Analysis.  Small  8vo,    i   25 

Grotenfelt's  Principles  of  Modern  Dairy  Practice.     (Woll.) i2mo,  2  oo 

Groth's  Introduction  to  Chemical  Crystallography  (Marshall) i2mo,  i  25 

Hammarsten's  Text-book  of  Physiological  Chemistry.     (Mandel.) 8vo,  4  oo 

Hanausek's  Microscopy  of  Technical  Products.     (Winton. ) 8vo,  5  oo 

*  Haskin's  and  MacLeod's  Organic  Chemistry 12mo,  2  oo 

Helm's  Principles  of  Mathematical  Chemistry.     (Morgan.) i2mo,    i  50 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  50 

Herrick's  Denatured  or  Industrial  Alcohol 8vo,    4  oo 

Hind's  Inorganic  Chemistry 8vo,  3  oo 

*  Laboratory  Manual  for  Students I2mo,  i  oo 

Holleman's  Text-book  of  Inorganic  Chemistry.     (Cooper.) 8vo,  2  50 

Text-book  of  Organic  Chemistry.     (Walker  and  Mott.) 8vo,  2  50 

*  Laboratory  Manual  of  Organic  Chemistry.     (Walker.) I2mo,  i  oo 

4 


3  oo 
5  oo 
i  25 


2  50 

1  00 

3  00 

2  00 
I  00 

7  50 

3  oo 
3  oo 
3  oo 
i  oo 
i  50 


Holley  and  Ladd's  Analysis  of  Mixed  Paints,  Color  Pigments ,  and  Varnishes. 
(In  Press) 

Hopkins's  Oil-chemists'  Handbook 8vo, 

Iddings's  Rock  Minerals 8vo, 

Jackson's  Directions  for  Laboratory  Work  in  Physiological  Chemistry.  .8vo, 
Johannsen's  Key  for  the  Determination  of  Rock-forming  Minerals  in  Thin  Sec- 
tions.    (In  Press) 

Keep's  Cast  Iron 8vo, 

Ladd's  Manual  of  Quantitative  Chemical  Analysis ismo, 

Landauer's  Spectrum  Analysis.     (Tingle.) 8vo, 

*  Langworthy   and   Austen.        The   Occurrence   of  Aluminium  in  Vegetable 

Products,  Animal  Products,  and  Natural  Waters 8vo, 

Lassar-Cohn's  Application  of  Some  General  Reactions  to  Investigations  in 

Organic  Chemistry.  (Tingle.) i2mo, 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control 8vo, 

Lob's  Electrochemistry  of  Organic  Compounds.  (Lorenz.) 8vo, 

Lodge's  Notes  on  Assaying  and  Metallurgical  Laboratory  Experiments 8vo, 

Low's  Technical  Method  of  Ore  Analysis 8vo, 

Lunge's  Techno-chemical  Analysis.  (Conn.) I2mo 

*  McKay  and  Larsen's  Principles  and  Practice  of  Butter-making 8vo, 

Maire's  Modern  Pigments  and  their  Vehicles.     (In  Press.) 

Mandel's  Handbook  for  Bio-chemical  Laboratory I2mo, 

*  Martin's  Laboratory  Guide  to  Qualitative  Analysis  with  the  Blowpipe.  .  12 mo, 
Mason's  Water-supply.     (Considered  Principally  from  a  Sanitary  Standpoint.) 

3d  Edition,  Rewritten 8vo, 

Examination  of  Water.     (Chemical  and  Bacteriological.) I2mo, 

Matthew's  The  Textile  Fibres.    20!  Edition,  Rewritten 8vo, 

Meyer's  Determination  of  Radicles  in  Carbon  Compounds.     (Tingle.).  .I2mo, 

Miller's  Manual  of  Assaying I2mo, 

Cyanide  Process I2mo, 

Minet's  Production  of  Aluminum  and  its  Industrial  Use.     (Waldo.)-  •  •  •  i2mo, 

Mixter's  Elementary  Text-book  of  Chemistry I2mo, 

Morgan's  An  Outline  of  the  Theory  of  Solutions  and  its  Results I2mo, 

Elements  of  Physical  Chemistry . I2mo, 

*  Physical  Chemistry  for  Electrical  Engineers I2mo, 

Morse's  Calculations  used  in  Cane-sugar  Factories i6mo,  morocco, 

*  MUT'S  H  story  of  Chemical  Theories  and  Laws 8vo, 

Mulliken's  General  Method  for  the  Identification  of  Pure  Organic  Compounds. 

VoL  I Large  8vo, 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo, 

Ostwald's  Conversations  on  Chemistry.     Part  One.     (Ramsey.) I2mo, 

"  "  "  Part  Two.     (Turnbull.) i2mo, 

*  Palmer's  Practical  Test  Book  of  Chemistry 12mo, 

*  Pauli's  Physical  Chemistry  in  the  Service  of  Medicine.     (Fischer.) .  .  .  .  i2mo, 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo,  paper, 

Pictet's  The  Alkaloids  and  their  Chemical  Constitution.     (Biddle.) 8vo, 

Pinner's  Introduction  to  Organic  Chemistry.     (Austen.) I2mo, 

Poole's  Calorific  Power  of  Fuels 8vo, 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis izmo, 

*  Reisig's  Guide  to  Piece-dyeing 8vo,  25  oo 

Richards  and  Woodman's  Air,  Water,  and  Food  from  a  Sanitary  Standpoint..8vo ,    2  oo 

Ricketts  and  Miller's  Notes  on  Assaying 8vo, 

Rideal's  Sewage  and  the  Bacterial  Purification  of  Sewage .*.  . .  .8vo, 

Disinfection  and  the  Preservation  of  Food 8vo, 

Riggs's  Elementary  Manual  for  the  Chemical  Laboratory 8vo, 

Robine  and  Lenglen's  Cyanide  Industry.     (Le  Clerc.) 8vo, 

5 


4  oo 
i  25 

4  oo 
00 

00 
00 

50 
50 
oo 

3  oo 

5  oo 

1  50 

4  oo 

5  oo 

2  00 

1  50 

2  OO 
1  00 

I  25 

50 

5  oo 
i  50 

3  oo 

i  25 


3  oo 

4  oo 
4  oo 
i  25 
4  oo 


Ruddiman's  Incompatibilities  in  Prescriptions 8vo,  2  oo 

*  Whys  in  Pharmacy lamo,  i  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish .8vOi  3  oo 

Salkowski's  Physiological  and  Pathological  Chemistry.     (Orndorff.) 8vo,  2  50 

Schimpf  s  Text-book  of  Volumetric  Analysis i2mo,  2  50 

Essentials  of  Volumetric  Analysis. i2mo,  i  25 

*  Qualitative  Chemical  Analysis 8vo,  i   25 

Smith's  Lecture  Notes  on  Chemistry  for  Dental  Students 8vo,  2  50 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses i6mo,  morocco  3  oo 

Handbook  for  Cane  Sugar  Manufacturers i6mo,  morocco.  3  oo 

Stockbridge's  Rocks  and  Soils 8vo,  2  50 

*  Tillman's  Elementary  Lessons  in  Heat 8vo,  i  50 

*  Descriptive  General  Chemistry 8vo»  3  oo 

Treadwell's  Qualitative  Analysis.     (Hall.) • 8vor  3  oo 

Quantitative  Analysis.     (Hall.) 8vo,  4  oo 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Van  Deventer's  Physical  Chemistry  for  Beginners.     (Boltwood.) i2mo,  i  50 

*  Walke's  Lectures  on  Explosives 8vo,  4  oo 

Ware's  Beet-sugar  Manufacture  and  Refining.     Vol.  I Small  8vo,  4  oo 

Vol.11 SmallSvo,  500 

Washington's  Manual  of  the  Chemical  Analysis  of  Rocks 8vo,  2  oo 

Weaver's  Military  Explosives 8vo,  3  oo 

Wehrenfennig's  Analysis  and  Softening  of  Boiler  Feed-Water 8vo,  4  oo 

Wells's  Laboratory  Guide  in»Qualitative  Chemical  Analysis 8vo,  i  50 

Short  Course  in  Inorganic  Qualitative  Chemical  Analysis  for  Engineering 

Students i2mo,  i  50 

Text-book  of  Chemical  Arithmetic i2mo,  i  25 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Wilson's  Cyanide  Processes i2mo,  i  50 

Chlorination  Process I2mo,  i  50 

Winton's  Microscopy  of  Vegetable  Foods 8vo,  7  5» 

Wulling's    Elementary    Course    in  Inortoaiuc,  Pharmaceutical,  and  Medical 

Chemistry - i2mo,  2  oo 


CIVIL  ENGINEERING. 

BRIDGES    AND   ROOFS.       HYDRAULICS.       MATERIALS   OF    ENGINEERING 
RAILWAY  ENGINEERING. 

Baker's  Engineers'  Surveying  Instruments I2mo,    3  oo 

Bixby's  Graphical  Computing  Table Paper  19^X24!  inches.         25 

Breed  and  Hosmer's  Principles  and  Practice  of  Surveying 8vo,   3  oo 

*  Burr's  Ancient  and  Modern  Engineering  and  the  Isthmian  Canal 8vo,    3  50 

Comstock's  Field  Astronomy  for  Engineers 8vo, 

*  CorthelTs  Allowable  Pressures  on  Deep  Foundations I2mo, 

Crandall's  Text-book  on  Geodesy  and  Least  Squares 8Vo, 

Davis's  Elevation  and  Stadia  Tables 8vo, 

Elliott's  Engineering  for  Land  Drainage i2mo, 

Practical  Farm  Drainage i2mo, 

*Fiebeger's  Treatise  on  Civil  Engineering 8vo,  5  oo 

Flemer's  Phototopographic  Methods  and  Instruments .8vo,  5  oo 

Folwell's  Sewerage.      (Designing  and  Maintenance.) 8vo,  3  oo 

Freitag's  Architectural  Engineering.     2d  Edition,  Rewritten 8vo,  3  5<> 

French  and  Ives'S  Stereotomy 8vo,  2  50 

Goodhue's  Municipal  Improvements i2mo,  i  50 

Gore's  Elements  of  Geodesy 8vo»  2  So 

*  Hauch  and  Rice's  Tables  of  Quantities  for  Preliminary  Estimates I2mo,  i  25 

Hayford's  Text-book  of  Geodetic  Astronomy 8vo,  3  oo. 

6 


Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  50 

Howe's  Retaining  Walls  for  Earth I2mo,  i   25 

Hoyt  and  Grover's  River  Discharge 8vo,  2  oo 

*  Ives's  Adjustments  of  the  Engineer's  Transit  and  Level i6mo,  Bds.         25 

Ives  and  Hilts's  Problems  in  Surveying i6mo,  morocco,  i  50 

Johnson's  (J.  B.)  Theory  and  Practice  of  Surveying Small  8vo,  4  oo 

Johnson's  (L.  J.)  Statics  by  Algebraic  and  Graphic  Methods 8vo,  2  oo 

Laplace's  Philosophical  Essay  on  Probabilities.    (Truscott  and  Emory.) .  i2mo,  2  oo 

Mahan's  Treatise  on  Civil  Engineering.     (1873.)     (Wood.) 8vo,  5  oo 

*  Descriptive  Geometry 8vo,  i  50 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy 8vo,  2  50 

Merriman  and  Brooks's  Handbook  for  Surveyors i6mo,  morocco,  2  oo 

Nugent's  Plane  Surveying 8vo,  3  50 

Ogden's  Sewer  Design I2mo,  2  oo 

Parsons's  Disposal  of  Municipal  Refuse. .  .8vo,  2  oo 

Patton's  Treatise  on  Civil  Engineering 8vo  half  leather,  7  50 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

Rideal's  Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  4  oo 

Riemer's  Shaft-sinking  under  Difficult  Conditions.     (Corning  and  Peele.) .  8vo,  3  oo 

Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry 8vo,  i  50 

Smith's  Manual  of  Topographical  Drawing.     (McMillan.) 8vo,  2  50 

Sondericker's  Graphic  Statics,  with  Applications  to  Trusses,  Beams,  and  Arches. 

8vo,  2  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

Tracy's  Plane  surveying I6mo,  morocco,  3  oo 

*  Trautwine's  Civil  Engineer's  Pocket-book i6mo,  morocco,  5  oo 

Venable's  Garbage  Crematories  in  America ., 8vo,  2  oo 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  8vo,  5  oo 

Sheep,  5  50 

Law  of  Contracts 8vo,  3  oo 

Warren's  Stereotomy — Problems  in  Stone-cutting 8vo,  2  50 

Webb's  Problems  in  the  Use  and  Adjustment  of  Engineering  Instruments. 

i6mo,  morocco,  i  25 

Wilson's  Topographic  Surveying 8vo,  3  50 

BRIDGES  AND  ROOFS. 

Boiler's  Practical  Treatise  on  the  Construction  of  Iron  Highway  Bridges.  .8vo,  2  oo 

Burr  and  Falk's  Influence  Lines  for  Bridge  and  Roof  Computations 8vo,  3  oo 

Design  and  Construction  of  Metallic  Bridges 8vo,  5  oo 

Du  Bois's  Mechanics  of  Engineering.     Vol.  II Small  4to,  10  oo 

Foster's  Treatise  on  Wooden  Trestle  Bridges 4to,  5  oo 

Fowler's  Ordinary  Foundations 8vo,  3  50 

Greene's  Roof  Trusses 8vo,  i  25  . 

Bridge  Trusses 8vo,  2  50 

Arches  in  Wood,  Iron,  and  Stone 8vo,  2  50 

Grimm's  Secondary  Stresses  in  Bridge  Trusses.     (In  Press.) 

Howe's  Treatise  on  Arches 8vo,  4  oo 

Design  of  Simple  Roof-trusses  in  Wood  and  Steel. 8vo,  2  oo 

Symmetrical  Masonry  Arches 8vo,  2  50 

Johnson,  Bryan,  and  Turneaure's  Theory  and  Practice  in  the  Designing  of 

Modern  Framed  Structures Small  4to,  10  oo 

Merriman  and  Jacoby's  Text- book  on  Roofs  and  Bridges: 

Part  I.    Stresses  in  Simple  Trusses 8vo,  2  50 

Part  II.    Graphic  Statics 8vo,  2  50 

Part  III.  Bridge  Design 8vo,  2  50 

Part  IV.   Higher  Structures 8vo,  2  50 

7 


Morison's  Memphis  Bridge 4to,  10  oo 

Waddell's  De  Pontibus,  a  Pocket-book  for  Bridge  Engineers.  .  i6mo,  morocco,    2  oo 

Specifications  for  Steel  Bridges i2mo,         50 

Wright's  Designing  of  Draw-spans.     Two  parts  in  one  volume 8vo,    3  50 


HYDRAULICS. 

Barnes's  Ice  Formation 8vo,  3  oo 

Bazin's  Experiments  upon  the  Contraction  of  the  Liquid  Vein  Issuing  from 

an  Orifice.     (Trautwine.).  , 8vo,  2  oo 

Bovey's  Treatise  on  Hydraulics 8vo,  5  oo 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Diagrams  of  Mean  Velocity  of  Water  in  Open  Channels ...  paper,  i  50 

Hydraulic  Motors.  .  « 8vo,  2  oo 

Coffin's  Graphical  Solution  of  Hydraulic  Problems i6mo,  morocco,  2  50 

Flather's  Dynamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Folwell's  Water-supply  Engineering 8vo,  4  oo 

Frizell's  Water-power 8vo,  5  oo 

Fuertes's  Water  and  Public  Health i2mo.  i   50 

Water-filtration  Works i2mo,  2  50 

Ganguillet  and  Kutter's  General  Formula  for  the  Uniform  Flow  of  Water  in 

Rivers  and  Other  Channels.     (Hering  and  Trautwine.) 8vo,  4  oo 

Hazen's  Clean  Water  and  How  to  Get  It Large  I2mo,  i  5o 

Filtration  of  Public  Water-supply 8vo,  3  oo 

Hazlehurst's  Towers  and  Tanks  for  Water-works 8vo,  2  50 

Herschel's  115  Experiments  on  the  Carrying  Capacity  of  Large,  Riveted,  Metal 

Conduits 8vo,  2  oo 

*Hubbard  and  Kiersted's  Water- works  Management  and  Maintenance..  .8vo,  4  co 
Mason's  Water-supply.     (Considered  Principally  from  a  Sanitary  Standpoint.) 

8vo,  4  oo 

Merriman's  Treatise  on  Hydraulics 8vo,  5  oo 

*  Michie's  Elements  of  Analytical  Mechanics 8vo,  4  oo 

Schuyler's  Reservoirs  for   Irrigation,    Water-power,   and   Domestic   Water- 
supply Large  8vo ,  5  oo 

*  Thomas  and  Watt's  Improvement  of  Rivers 4*0,  6  oo 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Wegmann's  Design  and  Construction  of  Dams.     5th  Edition,  enlarged.  .  .4to,  6  oo 

Water-supply  of  the  City  of  New  York  from  1658  to  1895 4to,  10  oo 

Whipple's  Value  of  Pure  Water Large  i2mo,  i  oo 

Williams  and  Hazen's  Hydraulic  Tables 8vo,  i  50 

Wilson's  Irrigation  Engineering , Small  8vo,  4  oo 

Wolff's  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Wood's  Turbines 8vo,  2  50 

Elements  of  Analytical  Mechanics 8vo,  3  oo 


MATERIALS  OF  ENGINEERING. 

Baker's  Treatise  on  Masonry  Construction 8vo,  5  oo 

Roads  and  Pavements 8yo,  5  oo 

Black's  United  States  Public  Works Oblong  4to,  5  oo 

*  Bovey's  Strength  of  Materials  and  Theory  of  Structures .8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering 8vo,  7  So 

Byrne's  Highway  Construction 8vo,  5  oo 

Inspection  of  the  Materials  and  Workmanship  Employed  in  Construction. 

i6mo,  3  oo 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Du  Bois's  Mechanics  of  Engineering.     Vol.  I Small  410  7  50 

*Eckel's  Cements,  Limes,  and  Plasters 8vo,  6  oo 

8 


Johnson's  Materials  of  Construction Large  8vo,  6  oo 

Fowler's  Ordinary  Foundations 8vo,  3  50 

Graves's  Forest  Mensuration 8vo,  4  oo 

*  Greene's  Structural  Mechanics 8vo,  2  50 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Martens's  Handbook  on  Testing  Materials.     (Henning.)     2  vols 8vo,  7  50 

Maurer's  Technical  Mechanics 8vo,  4  oo 

Merrill's  Stones  for  Building  and  Decoration 8vo,  5  oo 

Merriman's  Mechanics  of  Materials 8vo,  5  oo 

*  Strength  of  Materials I2mo,  i  oo 

Metcalf's  Steel.     A  Manual  for  Steel-users I2mo,  2  oo 

Patton's  Practical  Treatise  on  Foundations 8vo»  5  oo 

Richardson's  Modern  Asphalt  Pavements 8vo,  3  oo 

Richey's  Handbook  for  Superintendents  of  Construction i6mo,  mor.,  4  oo 

*  Ries's  Clays:  Their  Occurrence,  Properties,  and  Uses 8vo.  5  oo 

Rockwell's  Roads  and  Pavements  in  France I2mo,  i   25 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  acd  Varnish 8vo,  3  oo 

*Schwarz's  Longleaf  Pine  in  Virgin  Forest  ., i2mo,  i    25 

Smith's  Materials  of  Machines i2mo,  i  oo 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Spalding's  Hydraulic  Cement 1 2mo,  2  oo 

Text-book  on  Roads  and  Pavements I2mo,  2  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

Thurston's  Materials  of  Engineering.     3  Parts 8vo,  8  oo 

Part  I.     Non-metallic  Materials  of  Engineering  and  Metallurgy 8vo,  2  oo 

Part  II.     Iron  and  Steel 8vo,  3  50 

Part  IH.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Tillson's  Street  Pavements  and  Paving  Materials 8vo,  4  oo 

Turneaure  and  Maurer's  Principles  of  Reinforced  Concrete  Construction.   .8vo,  3  oo 

Waddell's  De  Pontibus.    (A  Pocket-book  for  Bridge  Engineers.).  .  i6mo.  mor.,  2  oo 

*  Specifications  for  Steel  Bridges 121110,  50 

Wood's  (De  V.)  Treatise  on  the  Resistance  of  Materials,  and  an  Appendix  on 

the  Preservation  of  Timber 8vo,  2  oo 

Wood's  (De  V.)  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Wood's  (M.  P.)  Rustless  Coatings:  Corrosion  and  Electrolysis  of  Iron  and 

Steel 8vo,  4  oo 


RAILWAY  ENGINEERING. 

Andrew's  Handbook  for  Street  Railway  Engineers 3x5  inches,  morocco,  i  25 

Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  oo 

Brook's  Handbook  of  Street  Railroad  Location i6mo,  morocco,  i  50 

Butt's  Civil  Engineer's  Field-book i6mo,  morocco,  2  50 

Crandall's  Transition  Curve i6mo,  morocco,  i  50 

Railway  and  Other  Earthwork  Tables 8vo,  I  50 

Crockett's  Methods  for  Earthwork  Computations.     (In  Press) 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book     i6mo,  morocco  5  oo 

Dredge's  History  of  the  Pennsylvania  Railroad:   (1879).  .  v Paper,  5  oo 

Fisher's  Table  of  Cubic  Yards Cardboard,  25 

Godwin's  Railroad  Engineers'  Field-book  and  Explorers'  Guide.  .  .  i6mo,  mor.,  2  50 
Hudson's  Tables  for  Calculating  the  Cubic  Contents  of  Excavations  and  Em- 
bankments  8vo,  i   oo 

Molitor  and  Beard's  Manual  for  Resident  Engineers i6mo,  i  oo 

Nagle's  Field  Manual  for  Railroad  Engineers i6mo,  morocco,  3  oo 

Philbrick's  Field  Manual  for  Engineers i6mo,  morocco,  3  oo 

Raymond's  Elements  of  Railroad  Engineering.     (In  Press.) 

9 


Searles's  Field  Engineering i6mo,  morocco,  3  oo 

Railroad  SpiraL i6mo,  morocco,  i  50 

Taylor's  Prismoidal  Formulae  and  Earthwork 8vo,  i  50 

*  Trautwine's  Method  of  Calculating  the  Cube  Contents  of  Excavations  and 

Embankments  by  the  Aid  of  Diagrams 8vo,  2  oo 

The  Field  Practice  of  Laying  Out  Circular  Curves  for  Railroads. 

1 2 mo,  morocco,  2  50 

Cross-section  Sheet Paper,  25 

Webb's  Railroad  Construction i6mo,  morocco,  5  oo 

Economics  of  Railroad  Construction Large  i2mo,  2  50 

Wellington's  Economic  Theory  of  the  Location  of  Railways Small  8vo,  5  oo 


DRAWING. 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

*  "                   "                   "       Abridged  Ed 8vo,  i  50 

Coolidge's  Manual  of  Drawing 8vo,  paper,  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  Engi- 
neers  v Oblong  4toj  2  50 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Emch's  Introduction  to  Projective  Geometry  and  its  Applications 8vo,  2  50 

Hill's  Text-book  on  Shades  and  Shadows,  and  Perspective 8vo,  2  oo 

Jamison's  Elements  of  Mechanical  Drawing 8vo,  2  50 

Advanced  Mechanical  Drawing 8vo,  2  oo 

Jones's  Machine  Design: 

Part  I.     Kinematics  of  Machinery. 8vo,  i  50 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

MacCord's  Elements  of  Descriptive  Geometry 8vo,  3  oo 

Kinematics;  or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4tov  4  oo 

Velocity  Diagrams 8vo,  i  50 

MacLeod's  Descriptive  Geometry Small  8vo,  i   50 

*  Mahan's  Descriptive  Geometry  and  Stone-cutting. .  .  .  .• 8vo,  i   50 

Industrial  Drawing.  (Thompson.) 8vo,  3  50 

Moyer's  Descriptive  Geometry 8vo,  2  oo 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

Reid's  Course  in  Mechanical  Drawing 8vo>  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo,  3  oo 

Robinson's  Principles  of  Mechanism. 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Smith's  (R.  S.)  Manual  of  Topographical  Drawing.  (McMillan.) 8vo,  2  50 

Smith  (A.  W.)  and  Marx's  Machine  Design 8vo,  3  oo 

*  Titsworth's  Elements  of  Mechanical  Drawing Oblong  8vo,  i   25 

Warren's  Elements  of  Plane  and  Solid  Free-hand  Geometrical  Drawing.  i2mo,  i  oo 

Drafting  Instruments  and  Operations 121110,  i  25 

Manual  of  Elementary  Projection  Drawing 12 mo,  i  50 

Manual  of  Elementary  Problems  in  the  Linear  Perspective  of  Form  and 

Shadow i2mo,  i  oo 

Plane  Problems  in  Elementary  Geometry i2mo,  i  25 

Elements  of  Descriptive  Geometry,  Shadows,  and  Perspective 8vo,  3  50 

General  Problems  of  Shades  and  Shadows 8vo,  3  oo 

Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

Problems,  Theorems,  and  Examples  in  Descriptive  Geometry 8vo,  2  50 

Weisbach's    Kinematics    and    Power    of    Transmission.        (Hermann    and 

Klein.) 8vo,  5  oo 

Whelpley's  Practical  Instruction  in  the  Art  of  Letter  Engraving i2mo.  2  oo 

Wilson's  (H.  M.)  Topographic  Surveying 8vo,  3  50 

10 


Wilson's  (V.  T.)  Free-hand  Perspective 8vo,  2  50 

Wilson's  (V.  T.)  Free-hand  Lettering 8vo,  i  oo 

Woolf's  Elementary  Course  in  Descriptive  Geometry Large  8vo,  3  oo 

ELECTRICITY  AND  PHYSICS. 

*  Abegg's  Theory  of  Electrolytic  Dissociation.     (Von  Ende.) i2mo,  i   25 

Anthony  and  Brackett's  Text-book  of  Physics.     (Magie.) Small  8vo,  3  oo 

Anthony's  Lecture-notes  on  the  Theory  of  Electrical  Measurements.  .  .  .  12 mo,  i  oo 

Benjamin's  History  of  Electricity 8vo,  3  oo 

Voltaic  Cell 8vo,  3  oo 

Betts's  Lead  Refining  and  Electrolysis.     (In  Press.) 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.     (Boltwood.).8vo,  3  oo 

*  Collins's  Manual  of  Wireless  Telegraphy i2mo,  i  50 

Morocco,  2  oo 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo,  3  oo 

*  Danneel's  Electrochemistry.     (Merriam.) 12 mo,  i   25 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  i6mo,  morocco,  5  oo 

.Dolezalek's  Theory  of  the  Lead  Accumulator  (Storage  Battery).   (Von  Ende.) 

1 2 mo,  2  50 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess.) 8vo,  4  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power 12010,  3  co 

Gilbert's  De  Magnete.     (Mottelay.) 8vo,  2  50 

Hanchett's  Alternating  Currents  Explained I2mo,  i  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  50 

Hobart  and  Ellis's  High-speed  Dynamo  Electric  Machinery.     (In  Presa.) 

Holman's  Precision  of  Measurements 8vo,  2  oo 

Telescopic   Mirror-scale  Method,  Adjustments,  and   Tests.  .  .  .Large  8vo,  75 
Karapetoff's  Experimental  Electrical  Engineering.     (In  Press.) 

Kinzbrunner's  Testing  of  Continuous-current  Machines 8vo,  2  oo 

Landauer's  Spectrum  Analysis.     (Tingle.) 8vo,  3  oo 

Le  Chateliers  High-temperature  Measurements.  (Boudouard — Burgess.)  12010,  3  oo 

Lob's  Electrochemistry  of  Organic  Compounds.     (Lorenz.) .8vo,  3  oo 

*  Lyons'?  Treatise  on  Electromagnetic  Phenomena.   Vols.  I.  and  II.  8vo,  each,  6  oo 

*  Michie's  Elements  of  Wave  Motion  Relating  to  Sound  and  Light 8vo,  4  oo 

Niaudet's  Elementary  Treatise  on  Electric  Batteries.     (Fishback.) i2mo,  2  50 

Morris's  Introduction  to  the  Study   of  Electrical  Engineering.     (In  Press.) 

*  Parshall  and  Hobart's  Electric  Machine  Design 4to,  half  morocco,  12  50 

Reagan's  Locomotives:    Simple,  Compound,  and  Electric.      New  Edition. 

Large  12 mo,  3  50 

*  Rosenberg's  Electrical  Engineering.     (Haldane  Gee — Kinzbrunner. ).  .  .8vo,  200 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     VoL  1 8vo,  2  50 

Thurston's  Stationary  Steam-engines 8vo,  2  50 

*  Tillman's  Elementary  Lessons  in  Heat 8vo,  i  50 

Tory  and  Pitcher's  Manual  of  Laboratory  Physics Small  8vo,  2  oo 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

LAW. 

*  Davis's  Elements  of  Law 8vo,  2  50 

*  Treatise  on  the  Military  Law  of  United  States 8vo,  7  oo 

*  Sheep,  7  SO 

*  Dudley's  Military  Law  and  the  Procedure  of  Courts- martial  .  .  .   Large  i2mo,  2  50 

Manual  for  Courts-martial i6mo,  morocco,  i  50 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  8vo  5  oo 

Sheep,  5  So 

Law  of  Contracts 8vo,  3  oo 

Winthrop's  Abridgment  of  Military  Law I2mo,  2  50 

11 


MANUFACTURES. 

Bernadou's  Smokeless  Powder — Nitro-cellulose  and  Theory  of  the  Cellulose 

Molecule 1 2mo ,  2  50 

Holland's  Iron  Founder 12010,  2  50 

The  Iron  Founder,"  Supplement 1 2mo,  2  50 

Encyclopedia  of  Founding  and  Dictionary  of  Foundry  Terms  Used  in  the 

Practice  of  Moulding i2mo,  3  oo 

*  Claassen's  Beet-sugar  Manufacture.    (Hall  and  Rolfe.) 8vo,  3  oo 

*  Eckel's  Cements,  Limes,  and  Plasters 8vo,  6  oo 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Effront's  Enzymes  and  their  Applications.     (Prescott.) 8vo,  3'  oo 

Fitzgerald's  Boston  Machinist 12010,  i  oo 

Ford's  Boiler  Making  for  Boiler  Makers i8mo.  i  oo 

Herrick's  Denatured  or  Industrial  Alcohol 8vo,  4   oo 

Honey  and  Ladd's  Analysis  of  Mixed  Paints,  Color  Pigments,  and  Varnishes. 

(In  Press.) 

Hopkins's  Oil-chemists'  Handbook 8vo,  3  oo 

Keep's  Cast  Iron 8vo,  2  50 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control Large  8vo,  7  50 

*  McKay  and  Larsen's  Principles  and  Practice  of  Butter-making 8vo,  i   50 

Maire's  Modern  Pigments  and  their  Vehicles.     (In  Press.) 

Matthews's  The  Textile  Fibres.     2d  Edition,  Rewritten 8vo,  4  oo 

Metcalf's  Steel.     A  Maunal  for  Steel -users i2mo,  2  oo 

Metcalf e's  Cost  of  Manufactures — And  the  Administration  of  Workshops .  .  8vo,  5  oo 

Meyer's  Modern  Locomotive  Construction 4to,  10  oo 

Morse's  Calculations  used  in  Cane-sugar  Factories i6mo,  morocco,  i   50 

*  Reisig's  Guide  to  Piece-dyeing 8vo,  25  oo 

Rice's  Concrete-block  Manufacture 8vo,  2  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Press-working  of  Metals 8vo,  3  oo 

Spalding's  Hydraulic  Cement i2mo,  2  oo 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses i6mo,  morocco,  3  oo 

Handbook  for  Cane  Sugar  Manufacturers i6mo,  morocco,  3  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

Thurston's  Manual  of  Steam-boilers,  their  Designs,  Construction  and  Opera- 
tion  8vo,  5  oo 

Ware's  Beet-sugar  Manufacture  and  Refining.     Vol.  I Small  8vo,  4  oo 

"               "                    "              **           "            Vol.  II 8vo,  5  oo 

Weaver's  Military  Explosives 8vo,  3  oo 

West's  American  Foundry  Practice i2mo,  2  50 

Moulder's  Text-book i2mo,  2  50 

Wolff's  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Wood's  Rustless  Coatings:   Corrosion  and  Electrolysis  of  Iron  and  Steel    ,8vo,  4  oo 


MATHEMATICS. 

Baker's  Elliptic  Functions 8vo, 

Briggs's  Elements  of  Plane  Analytic  Geometry 1 2mo, 

Buchanan's  Plane  and  Spherical  Trigonometry.     (In  Press.) 

Compton's  Manual  of  Logarithmic  Computations i2mo, 

Da  vis's  Introduction  to  the  Logic  of  Algebra 8vo, 

*  Dickson's  College  Algebra Large  1 2mo, 

*  Introduction  to  the  Theory  of  Algebraic  Equations Large  i2mo, 

Emch's  Introduction  to  Projective  Geometry  and  its  Applications 8vo, 

Halsted's  Elements  of  Geometry 8vo, 

Elementary  Synthetic  Geometry 8vo, 

*  Rational  Geometry 12 mo, 

12 


*  Johnson's  (J.  B.)  Three-place  Logarithmic  Tables:  Vest-pocket  size. paper,          15 

100  copies  for     5  oo 

*  Mounted  on  heavy  cardboard,  8X10  inches,         25 

10  copies  for     2  oo 
Johnson's  (W.  W.)  Elementary  Treatise  on  Differential  Calculus    .Small  8vo,     3  oo 

Elementary  Treatise  on  the  Integral  Calculus Small  8vo,     i   50 

Johnson's  (W.  W.)  Curve  Tracing  in  Cartesian  Co-ordinates 12 mo,      i   oo 

Johnson's  (W.  W.)  Treatise  on  Ordinary  and  Partial  Differential  Equations. 

Small  8vo,     3  50 

Johnson's  Treatise  on  the  Integral  Calculus Small  8vo,     3  oo 

Johnson's  (W.  W.)  Theory  of  Errors  and  the  Method  of  Least  Squares.  121110,      i   50 

*  Johnson's  (W.  W.)  Theoretical  Mechanics I2mo,     3  oo 

Laplace's  Philosophical  Essay  on  Probabilities.     (Truscott  and  Emory. ).i2mo,     2  oo 

*  Ludlow  and  Bass.     Elements  of  Trigonometry  and  Logarithmic  and  Other 

Tables 8vo,     3  oo 

Trigonometry  and  Tables  published  separately Each,     2  oo 

*  Ludlow's  Logarithmic  and  Trigonometric  Tables 8vo,     i  oo 

Manning's  IrrationalNumbers  and  their  Representation  by  Sequences  and  Series 

i2mo,     i   25 
Mathematical  Monographs.     Edited  by  Mansfield  Merriman  and  Robert 

S.  Woodward ., Octavo,  each     i  oo 

No.  i.  History  of  Modern  Mathematics,  by  David  Eugene  Smith. 
No.  2.  Synthetic  Projective  Geometry,  by  George  Bruce  Halsted. 
No.  3.  Determinants,  by  Laenas  Gifford  Weld.  No.  4.  Hyper- 
bolic Functions,  by  James  McMahon.  No.  S.  Harmonic  Func- 
tions, by  William  E.  Byerly.  No.  6.  Grassmann's  Space  Analysis, 
by  Edward  W.  Hyde.  No.  7.  Probability  and  Theory  of  Errors, 
by  Robert  S.  Woodward.  No.  8.  Vector  Analysis  and  Quaternions, 
by  Alexander  Macfarlane.  No.  9.  Differential  Equations,  by 
William  Woolsey  Johnson.  No.  10.  The  Solution  of  Equations, 
by  Mansfield  Merriman.  No.  n.  Functions  of  a  Complex  Variable, 
by  Thomas  S.  Fiske. 

Maurer's  Technical  Mechanics 8vo,    4  oo 

Merriman's  Method  of  Least  Squares. 8vo,     2  oo 

Rice  and  Johnson's  Elementary  Treatise  on  the  Differential  Calculus. .  Sm.  8vo,    3  oo 
Differential  and  Integral  Calculus.     2  vols.  in  one Small  8vo,    *  50 

*  Veblen  and  Lennes's  Introduction  to  the  Real  Infinitesimal  Analysis  of  One 

Variable 8vo,    2  oo 

Wood's  Elements  of  Co-ordinate  Geometry 8vo,     2  oo 

Trigonometry:   Analytical,  Plane,  and  Spherical I2mo,     i  oo 


MECHANICAL  ENGINEERING. 

MATERIALS  OF  ENGINEERING,  STEAM-ENGINES  AND  BOILERS. 

Bacon's  Forge  Practice i2mo,  i   50 

Baldwin's  Steam  Heating  for  Buildings I2mo,  2  50 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

*  "                   "                 "        Abridged  Ed 8vo,  i  50 

Benjamin's  Wrinkles  and  Recipes i2mo,  2  oo 

Carpenter's  Experimental  Engineering 8vo,  6  oo 

Heating  and  Ventilating  Buildings 8vo,  4  oo 

Clerk's  Gas  and  Oil  Engine Small  8vo,  4  oo 

Coolidge's  Manual  of  Drawing 8vo,  paper,  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  En- 
gineers  Oblong  4to,  2  50 

Cromwell's  Treatise  on  Toothed  Gearing I2mo,  i   50 

Treatise  on  Belts  and  Pulleys 12010,  i  50 

13 


Durley's  Kinematics  of  Machines 8vo, 

Flather's  Dynamometers  and  the  Measurement  of  Power i2mo, 

Rope  Driving i2mo,    2 

Gill's  Gas  and  Fuel  Analysis  for  Engineers 12010,     i 

Hall's  Car  Lubrication I2mo, 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco, 

Button's  The  Gas  Engine, 8vo, 

Jamison's  Mechanical  Drawing 8vo,    2 

Jones's  Machine  Design: 

Part  I.     Kinematics  of  Machinery 8vo, 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vo, 

Kent's  Mechanical  Engineers'  Pocket-book i6mo,  morocco, 

Kerr's  Power  and  Power  Transmission 8vo,     2 

Leonard's  Machine  Shop,  Tools,  and  Methods 8vo, 

*  Lorenz's  Modern  Refrigerating  Machinery.    (Pope,  Haven,  and  Dean.)  .  . 8vo, 
MacCord's  Kinematics;   or,  Practical  Mechanism. 8vo, 

Mechanical  Drawing 4to, 

Velocity  Diagrams 8vo, 

MacFar land's  Standard  Reduction  Factors  for  Gases 8vo,     i 

Mahan's  Industrial  Drawing.     (Thompson.) 8vo, 

Poole's  Calorific  Power  of  Fuels 8vo, 

Reid's  Course  in  Mechanical  Drawing 8vo, 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo, 

Richard's  Compressed  Air i2mo, 

Robinson's  Principles  of  Mechanism 8vo, 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo, 

Smith's  (O.)  Press-working  of  Metals 8vo, 

Smith  (A.  W.)  and  Marx's  Machine  Design 8vo, 

Thurston's    Treatise    on    Friction  and    Lost    Work    in    Machinery   and    Mill 
Work 8vo, 

Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics .  I2mo, 

Tillson's  Complete  Automobile  Instructor i6mo,     i 

Morocco, 

Warren's  Elements  of  Machine  Construction  and  Drawing 8vo, 

Weisbach's    Kinematics    and    the    Power    of    Transmission.     (Herrmann — 

Klein. ) 8vo,    5 

Machinery  of  Transmission  and  Governors.     (Berrmanri — Klein.).  .8vo,    5 

Wolff's  Windmill  as  a  Prime  Mover 8vo,    3 

Wood's  Turbines 8vo,    2 

MATERIALS   OF    ENGINEERING. 

*  Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,    7 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering.     6th  Edition. 

Reset 8vo,    7 

Church's  Mechanics  of  Engineering 8vo,    6 

*  Greene's  Structural  Mechanics 8vo,    2 

Johnson's  Materials  of  Construction 8vo,    6 

Keep's  Cast  Iron 8vo,     2 

Lanza's  Applied  Mechanics 8vo,    7 

Martens's  Bandbook  on  Testing  Materials.     (Benning.) 8vo,    7 

Maurer's  Technical  Mechanics 8vo, 

Merriman's  Mechanics  of  Materials 8vo, 

*  Strength  of  Materials i2mo, 

Metcalf's  Steel.     A  Manual  for  Steel-users i2mo, 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo, 

Smith's  Materials  of  Machines.' i2mo,     i 

Thurston's  Materials  of  Engineering 3  vols.,  8vo, 

Part  II.     Iron  and  Steel 8vo, 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,     2 

14 


Wood's  (De  V.)  Treatise  on  the  Resistance  of  Materials  and  an  Appendix  on 

the  Preservation  of  Timber 8vo,    2  oo 

Elements  of  Analytical  Mecnanics 8vo,    3  oo 

Wood's  (M.  P.)  Rustless  Coatings:    Corrosion  and  Electrolysis  of  Iron  and 

Steel 8vo,    4  oo 

STEAM-ENGINES  AND  BOILERS. 

Berry's  Temperature-entropy  Diagram i2mo,     i  25 

Carnot's  Reflections  on  the  Motive  Power  of  Heat     (Thurston.) I2mo,     i  50 

Creighton's  Steam-engine  and  other  Heat-motors 8vo,    500 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  . .  .i6mo,  mor.,    5  oo 

Ford's  Boiler  Making  for  Boiler  Makers i8mo,     i  oo 

Goss's  Locomotive  Sparks 8vo,    2  oo 

Locomotive  Performance 8vo,   5  oo 

Hemenway's  Indicator  Practice  and  Steam-engine  Economy 12 mo,     2  oo 

Button's  Mechanical  Engineering  of  Power  Plants 8vo,     5  oo 

Heat  and  Heat-engines 8vo,     5  oo 

Kent's  Steam  boiler  Economy 8vo,    4  oo 

Kneass's  Practice  and  Theory  of  the  Injector 8vo,    i  50 

MacCord's  Slide-valves 8vo,    2  oo 

Meyer's  Modern  Locomotive  Construction 4to,  10  oo 

Peabody's  Manual  of  the  Steam-engine  Indicator I2mo.    i  50 

Tables  of  the  Properties  of  Saturated  Steam  and  Other  Vapors 8vo,     i  oo 

Thermodynamics  of  the  Steam-engine  and  Other  Heat-engines 8vo,    5  oo 

Valve-gears  for  Steam-engines 8vo,    2  50 

Peabody  and  Miller's  Steam-boilers 8vo,    4  oo 

Pray's  Twenty  Years  with  the  Indicator Large  8vo,    2  50 

Pupin's  Thermodynamics  of  Reversible  Cycles  in  Gases  and  Saturated  Vapors. 

(Osterberg.) i2mo,    i  25 

Reagan's  Locomotives:    Simple,  Compound,  and  Electric.     New  Edition. 

Large  12 mo,    3  50 

Sinclair's  Locomotive  Engine  Running  and  Management I2mo,    2  oo 

Smart's  Handbook  of  Engineering  Laboratory  Practice 12 mo,    2  50 

Snow's  Steam-boiler  Practice 8vo,    3  oo 

Spangler's  Valve-gears .. 8vo,     2  50 

Notes  on  Thermodynamics I2mo,    i  oo 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,    3  oo 

Thomas's  Steam-turbines 8vo,    3  50 

Thurston's  Handy  Tables 8vo,     i  50 

Manual  of  the  Steam-engine 2  vols.,  8vo,  10  oo 

Part  I.     History,  Structure,  and  Theory. 8vo,    6  oo 

Part  II.     Design,  Construction,  and  Operation 8vo,    6  oo 

Handbook  of  Engine  and  Boiler  Trials,  and  the  Use  of  the  Indicator  and 

the  Prony  Brake 8vo,    5  oo 

Stationary  Steam-engines 8vo,    2  50 

Steam-boiler  Explosions  in  Theory  and  in  Practice i2mo,    i  50 

Manual  of  Steam-boilers,  their  Designs,  Construction,  and  Operation .  8vo,    5  oo 
Wehrenfenning's  Analysis  and  Softening  of  Boiler  Feed-water  (Patterson)  8vo,     4  oo 

Weisbach's  Heat,  Steam,  and  Steam-engines.     (Du  Bois.) 8vo,    5  oo 

Whitham's  Steam-engine  Design 8vo,    5  oo 

Wood's  Thermodynamics,  Heat  Motors,  and  Refrigerating  Machines.  .  .8vo,    4  oo 


MECHANICS  AND   MACHINERY. 

Barr's  Kinematics  of  Machinery 8<ro,  2  50 

*  Bovey's  Strength  of  Materials  and  Theory  of  Structures   8vo,  7  50 

Chase's  The  Art  of  Pattern-making I2mo,  2  50 

15 


Church's  Mechanics  of  Engineering 8vo,  6  oo 

Notes  and  Examples  in  Mechanics Svo,  2  oo 

Compton's  First  Lessons  in  Metal-working rarno,  i  50 

Compton  and  De  Groodt's  The  Speed  Lathe i2mo,  i  50 

Cromwell's  Treatise  on  Toothed  Gearing i2mo,  i  50 

Treatise  on  Belts  and  Pulleys i2mo,  i  50 

Dana's  Text-book  of  Elementary  Mechanics  for  Colleges  and  Schools.  .  12 mo,  i  50 

Dingey's  Machinery  Pattern  Making i2mo,  2  oo 

Dredge's  Record  of  the   Transportation  Exhibits  Building  of  the   World's 

Columbian  Exposition  of  1893 4to  half  morocco,  5  oo 

Du  Bois's  Elementary  Principles  of  Mechanics : 

Vol.      I.     Kinematics 8vo,  3  50 

Vol.    II.     Statics 8vo,  4  oo 

Mechanics  of  Engineering.     Vol.    I Small  4to,  7  50 

VoL  II Small  4to,  10  oo 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Fitzgerald's  Boston  Machinist i6mo,  i  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Rope  Driving i2mo,  2  oo 

Goss's  Locomotive  Sparks 8vo,  2  oo 

Locomotive  Performance 8vo,  5  oo 

*  Greene's  Structural  Mechanics. 8vo,  2  50 

Hall's  Car  Lubrication „.  .  .  i2mo,  i  oo 

Hobart  and  Ellis 's  High-speed  Dynamo  Electric  Machinery.     (In  Press.) 

Holly's  Art  of  Saw  Filing i8mo,  75 

James's  Kinematics  of  a  Point  and  the  Rational  Mechanics  of  a  Particle. 

Small  8vo,  2  oo 

*  Johnson's  (W.  W.)  Theoretical  Mechanics i2ino,  3  oo 

Johnson's  (L.  J.)  Statics  by  Graphic  and  Algebraic  Methods 8vo,  2  oo 

Jones's  Machine  Design: 

Part    I.     Kinematics  of  Machinery 8vo,  i  50 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

Kerr's  Power  and  Power  Transmission Svo,  2  oo 

Lanza's  Applied  Mechanics 8vo,  7  50 

Leonard's  Machine  Shop,  Tools,  and  Methods Svo,  4  oo 

*  Lorenz's  Modern  Refrigerating  Machinery.     (Pope,  Haven,  and  Dean.). Svo,  4  oo 
MacCord's  Kinematics;  or,  Practical  Mechanism Svo,  5  oo 

Velocity  Diagrams Svo,  i  50 

*  Martin's  Text  Book  on  Mechanics,  Vol.  I,  Statics i2mo,  i   25 

*  Vol.  2,  Kinematics  and  Kinetics  .  -I2mo,  1  50 

Maurer's  Technical  Mechanics Svo,  4  oo 

Merriman's  Mechanics  of  Materials Svo,  5  oo 

*  Elements  of  Mechanics i2mo,  i  oo 

*  Michie's  Elements  of  Analytical  Mechanics Svo,  4  oo 

*  Parshall  and  Hobart's  Electric  Machine  Design 4to,  half  morocco,  12  50 

Reagan's  Locomotives :  Simple,  Compound,  and  Electric.     New  Edition. 

Large  i2mo,  3  5o 

Reid's  Course  in  Mechanical  Drawing Svo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. Svo,  3  oo 

Richards's  Compressed  Air i2mo,  i  50 

Robinson's  Principles  of  Mechanism Svo,  3  oo 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.  Vol.  I .  .8vo,  2  50 

Sanborn's  Mechanics:  Problems Large  i2mo,  i  50 

Schwamb  and  Merrill's  Elements  of  Mechanism ,  . .  .Svo,  3  oo 

Sinclair's  Locomotive-engine  Running  and  Management i2mo,  2  oo 

Smith's  (O.)  Press-working  of  Metals Svo,  3  oo 

Smith's  (A.  W.)  Materials  of  Machines i2mo,  i  oo 

Smith  (A.  W.)  and  Marx's  Machine  Design , Svo,  3  oo 

Sorel' s  Carbureting  and  Combustion  of  Alcohol  Engines.  (Woodward  and 

Preston.) Large  8vo,  3  oo 

16 


SpangJer,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo.  3  oo 

Thurston's  Treatise  on  Friction  and  Lost  Work  in    Machinery  and    Mill 

Work 8vo,  3  oo 

Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics.  12010,  i  oo 

Tillson's  Complete  Automobile  Instructor i6mo,  i   50 

Morocco,  2  o« 

Warren's  Elements  of  Machine  Construction  and  Drawin* 8vo,  7  50 

Weisbach's  Kinematics  and  Power  of  Transmission.    (Herrmann — Klein.). 8vo.  5  oo 

Machinery  of  Transmission  and  Governors.      (Herrmann — Klein. ).8vo.  5  oo 

Wood's  Elements  of  Analytical  Mechanics '. 8vo,  3  oo 

Principles  of  Elementary  Mechanics I2mo,  i  25 

Turbines 8vo,  2  50 

The  World's  Columbian  Exposition  of  1893 4to,  i  oo 

MEDICAL. 

*  Bolduan's  Immune  Sera I2mo,  l  50 

De  Fursac's  Manual  of  Psychiatry.     (Rosanoff  and  Collins. ).          Large  12 mo,  2  50 

Ehrlich's  Collected  Studies  on  Immunity.     (Bolduan.) 8vo,  6  oo 

*  Fischer's  Physiology  of  Alimentation Large  I2mo,  cloth,  2  oo 

Hammarsten's  Text-book  on  Physiological  Chemistry.     (Mandel. ) 8vo,  4  oo 

Lassar-Cohn's  Practical  Urinary  Analysis.     (Lorenz.) .  i2mo,  i  oo 

*  Pauli's  Physical  Chemistry  in  the  Service  of  Medicine.     (Fischer.)          i2mo,  i   25 

*  Pozzi-Escot's  The  Toxins  and  Venoms  and  their  Antibodies.     (Cohn.).  i2mo,  i  oo 

Rostoski's  Serum  Diagnosis.     (Bolduan.) i2mo.  i  oo 

Salkowski's  Physiological  and  Pathological  Chemistry.     (Orndorff.) 8vo,  2  50 

*  Satterlee's  Outlines  of  Human  Embryology ...  i2mo,  i  25 

Steel's  Treatise  on  the  Diseases  of  the  Dog 8vo,  3  50 

Von  Behring's  Suppression  of  Tuberculosis.     (Bolduan.) i2mo,  i  oo 

Woodhull's  Notes  on  Military  Hygiene i6mo,  i  50 

*  Personal  Hygiene i2mo,  i  oo 

Wulling's  An  Elementary  Course  in  Inorganic  Pharmaceutical  and  Medical 

Chemistry 1 2mo,  2  oo 

METALLURGY. 

Belts' s  Lead  Refining  by  Electrolysis.    (In  Press.) 

Egleston's  Metallurgy  of  Silver,  Gold,  and  Mercury; 

Vol.    I.     Silver 8vo,  750 

Vol.  II.     Gold  and  Mercury 8vo,  7  50 

Goesel's  Minerals  and  Metals:     A  Reference  Book i6mo,  mor.  3  oo 

*  Iles's  Lead-smelting i2mo,  2  50 

Keep's  Cast  Iron 8vo,  2  50 

Kunhardt's  Practice  of  Ore  Dressing  in  Europe 8vo,  i  50 

Le  Chatelier's  High-temperature  Measurements.  (Boudouard — Burgess.  )i2mo,  3  oo 

Metcalf's  Steel.     A  Manual  for  Steel-users.  .  , i2rno,  2  oo 

Miller's  Cyanide  Process i2mo,  i  oo 

Minet's  Production  of  Aluminum  and  its  Industrial  Use.     (Waldo.). . .  .  i2mo,  2  50 

Robine  and  Lenglen's  Cyanide  Industry.     (Le  Clerc.) 8vo,  4  oo 

Smith's  Materials  of  Machines I2mo,  i  oo 

Thurston's  Materials  of  Engineering.     In  Three  Parts 8vo,  8  eo 

Part    II.     Iron  and  Steel '     8vo,  3  50 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vOf  2  5O 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

MINERALOGY. 

Barringer's  Description  of  Minerals  of  Commercial  Value.    Oblong,  morocco,  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo  3  oo 

17 


Boyd's  Map  of  Southwest  Virignia Pocket-book  form.  2  oo 

*  Browning's  Introduction  to  the  Rarer  Elements 8vo,  i   50 

Brash's  Manual  of  Determinative  Mineralogy.     (Penfield.) 8vo,  4  oo 

Chester's  Catalogue  of  Minerals 8vo,  paper,  i  oo 

Cloth,  i  25 

Dictionary  of  the  Names  of  Minerals Svo,  3  50 

Dana's  System  of  Mineralogy Large  8vo,  half  leather,  12  50 

First  Appendix  to  Dana's  New  "  System  of  Mineralogy." Large  8vo,  i  oo 

Text-book  of  Mineralogy 8vo,  4  oo 

Minerals  and  How  to  Study  Them i2mo,  i  50 

Catalogue  of  American  Localities  of  Minerals Large  8vo,  i  oo 

Manual  of  Mineralogy  and  Petrography i2mo  2  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects i2mo,  i  oo 

Eakle's  Mineral  Tables 8vo,  i  25 

Egleston's  Catalogue  of  Minerals  and  Synonyms • 8vo,  2  50 

Goesel's  Minerals  and  Metals :     A  Reference  Book ibmo,  mor.  3  oo 

Groth's  Introduction  to  Chemical  Crystallography  (Marshall) 12 mo,  i  25 

Iddings's  Rock  Minerals Svo,  5  oo 

Johannsen's  Key  for  the  Determination  of  Rock-forming  Minerals   in   Thin 
Sections.    (In  Press.) 

*  Martin's  Laboratory  Guide  to  Qualitative  Analysis  with  the  Blowpipe.  I2mo,  60 
Merrill's  Non-metallic  Minerals.   Their  Occurrence  and  Uses Svo,  4  oo 

Stones  for  Building  and  Decoration                      ..  Svo,  5  oo 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

Svo,  paper,  50 

Tables  of  Minerals Svo,  i  00 

*  Richards's  Synopsis  of  Mineral  Characters.. . i2mo.  morocco,  i   25 

*  Ries's  Clays.  Their  Occurrence.  Properties,  and  Uses.. Svo,  5  oo 

Rosenbusch's    Microscopical   Physiography    of    the    Rock-making  Minerals. 

(Iddings. ) : . .  .  Svo,  5  oo 

*  Tillman's  Text-book  of  Important  Minerals  and  Rocks Svo,  2  oo 

MINING. 

Beard's  Mine  Gases  and  Explosions.     (In  Press.) 

Boyd's  Resources  of  Southwest  Virginia Svo,  3  oo 

Map  of  Southwest  Virginia Pocket-book  form,  2  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects i2mo,  I  oo 

Eissler's  Modern  High  Explosives - 8~o,  4  oo 

Goesel's  Minerals  and  Metals ;     A  Reference  Book i6mo,  mor.  3  oo 

Goodyear's  Coal-mines  of  the  Western  Coa;t  of  the  United  States i2mo,  2  50 

Ihlseng's  Manual  of  Mining Svo,  5  oo 

*  Iles's  Lead-smelting. i2mo,  2  50 

Kunhardt's  Practice  of  Ore  Dressing  in  Europe . .  .8vc,  i  50 

Miller's  Cyanide  Process i2mo,  i  oo 

O'DriscolJ's  Notes  on  the  Treatment  of  Gold  Ores Svo,  2  oo 

Robine  and  Lenglen's  Cyanide  Industry.     (Le  Clerc.) Svo,  4  oo 

Weaver's  Military  Explosives Svo,  3  oo 

Wilson's  Cyanide  Processes , i2mo,  i  50 

Chlorination  Process.  . limo,  i  50 

Hydraulic  and  Placer  Mining.     2d  edition,  rewritten i2mo,  2  50 

Treatise  ojn  Practical  and  Theoretical  Mine  Ventilation :  T2mo,  i  25 

SANITARY  SCIENCE. 

Bashore's  Sanitation  of  a  Country  House i2mo ,  i  oo 

*  Outlines  of  Practical  Sanitation i2mo,  i  25 

Folwell's  Sewerage.     (Designing,  Construction,  and  Maintenance.) Svo,  3  oo 

Water-supply  Engineering Svo,  4  oo 

18 


Fowler's  Sewage  Works  Analyses 12013,  2  oo 

Fuertes's  Water  and  Public  Health i2mo,  i  50 

Water-filtration  Works 12010,  2  50 

Gerhard's  Guide  to  Sanitary  House-inspection  .    i6mo.  i  oo 

Sanitation  of  Public  Buildings 12mo,  1  50 

Hazen's  Filtration  of  Public  Water-supplies 8vo,  3  oo 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control Svo,  7  50 

Mason's  Water-supply.  (Considered  principally  from  a  Sanitary  Standpoint)  8vo,  4  oo 

Examination  of  Water.     (Chemical  and  Bacteriological.) 121110,  j  23 

*  Merriman's  Elements  of  Sanitary  Engineering Svo,,  2  oo 

Ogden's  Sewer  Design 12010,  2  oo 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis i2mo,  i  25 

*  Price's  Handbook  on  Sanitation 1 2 mo,  x  50 

Richards's  Cost  of  Food.     A  Study  in  Dietaries I2mo,  i  oo 

Cost  of  Living  as  Modified  by  Sanitary  Science i2mo,  i  oo 

Cost  of  Shelter i2mo,  I  oo 

Richards  and  Woodman's  Air    Water,  and  Food  from  a  Sanita-y  Stand- 
point  8vo,  2  oo 

*  Richards  and  Williams's  The  Dietary  Computer 8vo,  i  50 

Rideal's  S  wage  and  Bacterial  Purification  of  Sewage 8vo,  4  oo 

Disinfection  and  the  Preservation  of  Food 8vo,  400 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Von  Behring's  Suppression  of  Tuberculosis.     (Bolduan.) 12010,  i  oo 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Wilson's  Air  Conditioning.     (In  Press.) 

Winton's  Microscopy  of  Vegetable  Foods 8vo,  7  So 

Woodhull's  Notes  on  Military  Hygiene iCmo,  i  50 

*  Personal  Hygiene 12010,  i  oo 


MISCELLANEOUS. 

Association  of   State   and  National  Food  and  Dairy  Departments  (Interstate 
Pure  Food  Commission) : 

Tenth  Annual  Convention  Held  at  Hartford.  July   17-20,  1906.  ...8vo,     3  oo 
Eleventh    Annual    Convention,    Held  at  Jamestown    Tri-Centennial 

Exposition,  July  16-19,   1907.     (In  Press.) 
JEmmons's  Geological  Guide-book  of  the  Rocky  Mountain  Excursion  of  the 

International  Congress  of  Geologists Large  £vo,    I  50 

Fen-el's  Popular  Treatise  on  the  Winds 8vo,     4  oo 

Gannett's  Statistical  Abstract  of  the  World    241110.        75 

Gerhard's  The  Modern  Bath  and  Bath-houses.     (In  Press.) 

Haines's  American  Railway  Management I2mo,    2  50 

Ricketts's  History  of  Rensselaer  Polytechnic  Institute,  1824-1894.  .Small  8vo,    3  oo 

Rotherham's  Emphasized  New  Testament Large  Svo,    2  oo 

Standage's  Decorative  Treatment  of  Wood,  Glass,  Metal,  etc.     (In  Press.) 

The  World's  Columbian  Exposition  of  1893 4to,     i  oo 

Winslow's  Elements  of  Applied  Microscopy I2mo,     i  50 


HEBREW  AND  CHALDEE  TEXT-BOOKS. 

Green's  Elementary  Hebrew  Grammar I2mo,     i  25 

Hebrew  Chrestomathy Svo,    2  oo 

Gesenius's  Hebrew  and  Chaldee  Lexicon  to  the  Old  Testament  Scriptures. 

(Tregelles.) Small  4to,  half  morocco,    5  oo 

Letteris's  Hebrew  Bible Svo,    2  25 

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